From b004ef5448376c3d5d7868b38ee27b3c2294d13d Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 09:42:08 +0100
Subject: [PATCH 01/10] Pull the error object out of isolated-vm when a user
 script throws an error.

---
 .../src/jsRunner/tests/jsRunner.spec.ts       |  2 +-
 .../server/src/jsRunner/vm/isolated-vm.ts     | 22 ++++++++++++++++++-
 .../src/helpers/javascript.ts                 |  3 +++
 3 files changed, 25 insertions(+), 2 deletions(-)

diff --git a/packages/server/src/jsRunner/tests/jsRunner.spec.ts b/packages/server/src/jsRunner/tests/jsRunner.spec.ts
index 525f6d865e..2b9fc08041 100644
--- a/packages/server/src/jsRunner/tests/jsRunner.spec.ts
+++ b/packages/server/src/jsRunner/tests/jsRunner.spec.ts
@@ -44,7 +44,7 @@ describe("jsRunner (using isolated-vm)", () => {
     const output = await processJS(
       `return this.constructor.constructor("return process.env")()`
     )
-    expect(output).toBe("Error while executing JS")
+    expect(output).toBe("ReferenceError: process is not defined")
   })
 
   describe("helpers", () => {
diff --git a/packages/server/src/jsRunner/vm/isolated-vm.ts b/packages/server/src/jsRunner/vm/isolated-vm.ts
index 87d5b966c2..e502b799bd 100644
--- a/packages/server/src/jsRunner/vm/isolated-vm.ts
+++ b/packages/server/src/jsRunner/vm/isolated-vm.ts
@@ -17,6 +17,15 @@ class ExecutionTimeoutError extends Error {
   }
 }
 
+class UserScriptError extends Error {
+  constructor(readonly userScriptError: Error) {
+    super(
+      `error while running user-supplied JavaScript: ${userScriptError.message}`,
+      { cause: userScriptError }
+    )
+  }
+}
+
 export class IsolatedVM implements VM {
   private isolate: ivm.Isolate
   private vm: ivm.Context
@@ -29,6 +38,7 @@ export class IsolatedVM implements VM {
 
   private readonly resultKey = "results"
   private runResultKey: string
+  private runErrorKey: string
 
   constructor({
     memoryLimit,
@@ -47,6 +57,7 @@ export class IsolatedVM implements VM {
     this.jail.setSync("global", this.jail.derefInto())
 
     this.runResultKey = crypto.randomUUID()
+    this.runErrorKey = crypto.randomUUID()
     this.addToContext({
       [this.resultKey]: { [this.runResultKey]: "" },
     })
@@ -216,7 +227,13 @@ export class IsolatedVM implements VM {
       }
     }
 
-    code = `results['${this.runResultKey}']=${this.codeWrapper(code)}`
+    code = `
+      try {
+        results['${this.runResultKey}']=${this.codeWrapper(code)}
+      } catch (e) {
+        results['${this.runErrorKey}']=e
+      }
+    `
 
     const script = this.isolate.compileScriptSync(code)
 
@@ -227,6 +244,9 @@ export class IsolatedVM implements VM {
 
     // We can't rely on the script run result as it will not work for non-transferable values
     const result = this.getFromContext(this.resultKey)
+    if (result[this.runErrorKey]) {
+      throw new UserScriptError(result[this.runErrorKey])
+    }
     return result[this.runResultKey]
   }
 
diff --git a/packages/string-templates/src/helpers/javascript.ts b/packages/string-templates/src/helpers/javascript.ts
index 3e16d8a07b..27a71da834 100644
--- a/packages/string-templates/src/helpers/javascript.ts
+++ b/packages/string-templates/src/helpers/javascript.ts
@@ -100,6 +100,9 @@ export function processJS(handlebars: string, context: any) {
     if (error.name === "ExecutionTimeoutError") {
       return "Request JS execution limit hit"
     }
+    if ("userScriptError" in error) {
+      return error.userScriptError.toString()
+    }
     return "Error while executing JS"
   }
 }

From fdbe633b02be6adfe6956a3c08347dcf193d06cb Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 12:43:57 +0100
Subject: [PATCH 02/10] Get errors working on the client side as well.

---
 .../bindings/EvaluationSidePanel.svelte       | 27 ++++++++++++-------
 packages/string-templates/src/index.ts        | 16 +++++++++++
 2 files changed, 33 insertions(+), 10 deletions(-)

diff --git a/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte b/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
index 2c4e6a0991..3b71fad715 100644
--- a/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
+++ b/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
@@ -8,22 +8,29 @@
   export let evaluating = false
   export let expression = null
 
-  $: error = expressionResult === "Error while executing JS"
+  $: error = expressionResult && expressionResult.error != null
   $: empty = expression == null || expression?.trim() === ""
   $: success = !error && !empty
   $: highlightedResult = highlight(expressionResult)
 
-  const highlight = json => {
-    if (json == null) {
+  const highlight = result => {
+    if (result == null) {
       return ""
     }
-    // Attempt to parse and then stringify, in case this is valid JSON
-    try {
-      json = JSON.stringify(JSON.parse(json), null, 2)
-    } catch (err) {
-      // Ignore
+
+    let str
+    if (result.error) {
+      str = result.error.toString()
+    } else {
+      // Attempt to parse and then stringify, in case this is valid result
+      try {
+        str = JSON.stringify(JSON.parse(result.result), null, 2)
+      } catch (err) {
+        // Ignore
+      }
     }
-    return formatHighlight(json, {
+
+    return formatHighlight(str, {
       keyColor: "#e06c75",
       numberColor: "#e5c07b",
       stringColor: "#98c379",
@@ -34,7 +41,7 @@
   }
 
   const copy = () => {
-    let clipboardVal = expressionResult
+    let clipboardVal = expressionResult.result
     if (typeof clipboardVal === "object") {
       clipboardVal = JSON.stringify(clipboardVal, null, 2)
     }
diff --git a/packages/string-templates/src/index.ts b/packages/string-templates/src/index.ts
index 8d5fe4c16d..69ca05ef76 100644
--- a/packages/string-templates/src/index.ts
+++ b/packages/string-templates/src/index.ts
@@ -463,6 +463,22 @@ export function defaultJSSetup() {
         setTimeout: undefined,
       }
       createContext(context)
+
+      js = `
+        result = {
+          result: null,
+          error: null,
+        };
+
+        try {
+          result.result = ${js};
+        } catch (e) {
+          result.error = e.toString();
+        }
+
+        result;
+      `
+
       return runInNewContext(js, context, { timeout: 1000 })
     })
   } else {

From df242cc2ad25978786b5da80045579fde989241c Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 13:07:22 +0100
Subject: [PATCH 03/10] Don't break the fact that processStringSync returns a
 string.

---
 .../common/bindings/BindingPanel.svelte       | 16 ++++++---
 .../bindings/EvaluationSidePanel.svelte       | 33 +++++++++++--------
 .../server/src/jsRunner/vm/isolated-vm.ts     |  2 ++
 .../src/utilities/rowProcessor/utils.ts       |  9 ++++-
 packages/string-templates/src/errors.ts       | 10 ++++++
 .../src/helpers/javascript.ts                 |  4 +--
 packages/string-templates/src/index.ts        | 14 ++++++--
 7 files changed, 64 insertions(+), 24 deletions(-)

diff --git a/packages/builder/src/components/common/bindings/BindingPanel.svelte b/packages/builder/src/components/common/bindings/BindingPanel.svelte
index d8edf0cbb1..2f39dc6f53 100644
--- a/packages/builder/src/components/common/bindings/BindingPanel.svelte
+++ b/packages/builder/src/components/common/bindings/BindingPanel.svelte
@@ -66,6 +66,7 @@
   let insertAtPos
   let targetMode = null
   let expressionResult
+  let expressionError
   let evaluating = false
 
   $: useSnippets = allowSnippets && !$licensing.isFreePlan
@@ -142,10 +143,16 @@
   }
 
   const debouncedEval = Utils.debounce((expression, context, snippets) => {
-    expressionResult = processStringSync(expression || "", {
-      ...context,
-      snippets,
-    })
+    try {
+      expressionError = null
+      expressionResult = processStringSync(expression || "", {
+        ...context,
+        snippets,
+      })
+    } catch (err) {
+      expressionResult = null
+      expressionError = err
+    }
     evaluating = false
   }, 260)
 
@@ -370,6 +377,7 @@
       {:else if sidePanel === SidePanels.Evaluation}
         <EvaluationSidePanel
           {expressionResult}
+          {expressionError}
           {evaluating}
           expression={editorValue}
         />
diff --git a/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte b/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
index 3b71fad715..2c5c1d4587 100644
--- a/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
+++ b/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
@@ -5,32 +5,35 @@
   import { fade } from "svelte/transition"
 
   export let expressionResult
+  export let expressionError
   export let evaluating = false
   export let expression = null
 
-  $: error = expressionResult && expressionResult.error != null
+  $: error = expressionError != null
   $: empty = expression == null || expression?.trim() === ""
   $: success = !error && !empty
   $: highlightedResult = highlight(expressionResult)
 
-  const highlight = result => {
-    if (result == null) {
+  const formatError = err => {
+    if (err.code === "USER_SCRIPT_ERROR") {
+      return err.userScriptError.toString()
+    }
+    return err.toString()
+  }
+
+  const highlight = json => {
+    if (json == null) {
       return ""
     }
 
-    let str
-    if (result.error) {
-      str = result.error.toString()
-    } else {
-      // Attempt to parse and then stringify, in case this is valid result
-      try {
-        str = JSON.stringify(JSON.parse(result.result), null, 2)
-      } catch (err) {
-        // Ignore
-      }
+    // Attempt to parse and then stringify, in case this is valid result
+    try {
+      json = JSON.stringify(JSON.parse(json), null, 2)
+    } catch (err) {
+      // Ignore
     }
 
-    return formatHighlight(str, {
+    return formatHighlight(json, {
       keyColor: "#e06c75",
       numberColor: "#e5c07b",
       stringColor: "#98c379",
@@ -80,6 +83,8 @@
   <div class="body">
     {#if empty}
       Your expression will be evaluated here
+    {:else if error}
+      {formatError(expressionError)}
     {:else}
       <!-- eslint-disable-next-line svelte/no-at-html-tags-->
       {@html highlightedResult}
diff --git a/packages/server/src/jsRunner/vm/isolated-vm.ts b/packages/server/src/jsRunner/vm/isolated-vm.ts
index e502b799bd..9262687925 100644
--- a/packages/server/src/jsRunner/vm/isolated-vm.ts
+++ b/packages/server/src/jsRunner/vm/isolated-vm.ts
@@ -11,6 +11,7 @@ import { iifeWrapper } from "@budibase/string-templates"
 import environment from "../../environment"
 
 class ExecutionTimeoutError extends Error {
+  code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
   constructor(message: string) {
     super(message)
     this.name = "ExecutionTimeoutError"
@@ -18,6 +19,7 @@ class ExecutionTimeoutError extends Error {
 }
 
 class UserScriptError extends Error {
+  code = "USER_SCRIPT_ERROR"
   constructor(readonly userScriptError: Error) {
     super(
       `error while running user-supplied JavaScript: ${userScriptError.message}`,
diff --git a/packages/server/src/utilities/rowProcessor/utils.ts b/packages/server/src/utilities/rowProcessor/utils.ts
index 0fa6f62807..3a1ce08ece 100644
--- a/packages/server/src/utilities/rowProcessor/utils.ts
+++ b/packages/server/src/utilities/rowProcessor/utils.ts
@@ -81,7 +81,14 @@ export async function processFormulas<T extends Row | Row[]>(
             ...row,
             [column]: tracer.trace("processStringSync", {}, span => {
               span?.addTags({ table_id: table._id, column, static: isStatic })
-              return processStringSync(formula, context)
+              try {
+                return processStringSync(formula, context)
+              } catch (err: any) {
+                if (err.code === "USER_SCRIPT_ERROR") {
+                  return err.userScriptError.toString()
+                }
+                throw err
+              }
             }),
           }
         }
diff --git a/packages/string-templates/src/errors.ts b/packages/string-templates/src/errors.ts
index 79a8a525ef..4c7cbdb360 100644
--- a/packages/string-templates/src/errors.ts
+++ b/packages/string-templates/src/errors.ts
@@ -1,3 +1,13 @@
 export class JsErrorTimeout extends Error {
   code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
 }
+
+export class UserScriptError extends Error {
+  code = "USER_SCRIPT_ERROR"
+
+  constructor(readonly userScriptError: Error) {
+    super(
+      `error while running user-supplied JavaScript: ${userScriptError.message}`
+    )
+  }
+}
diff --git a/packages/string-templates/src/helpers/javascript.ts b/packages/string-templates/src/helpers/javascript.ts
index 27a71da834..e1d7f3e8a3 100644
--- a/packages/string-templates/src/helpers/javascript.ts
+++ b/packages/string-templates/src/helpers/javascript.ts
@@ -100,8 +100,8 @@ export function processJS(handlebars: string, context: any) {
     if (error.name === "ExecutionTimeoutError") {
       return "Request JS execution limit hit"
     }
-    if ("userScriptError" in error) {
-      return error.userScriptError.toString()
+    if (error.code === "USER_SCRIPT_ERROR") {
+      throw error
     }
     return "Error while executing JS"
   }
diff --git a/packages/string-templates/src/index.ts b/packages/string-templates/src/index.ts
index 69ca05ef76..aceea1da7e 100644
--- a/packages/string-templates/src/index.ts
+++ b/packages/string-templates/src/index.ts
@@ -16,6 +16,7 @@ import { removeJSRunner, setJSRunner } from "./helpers/javascript"
 
 import manifest from "./manifest.json"
 import { ProcessOptions } from "./types"
+import { UserScriptError } from "./errors"
 
 export { helpersToRemoveForJs, getJsHelperList } from "./helpers/list"
 export { FIND_ANY_HBS_REGEX } from "./utilities"
@@ -230,6 +231,9 @@ export function processStringSync(
       return process(string)
     }
   } catch (err) {
+    if (err.code === "USER_SCRIPT_ERROR") {
+      throw err
+    }
     return input
   }
 }
@@ -448,7 +452,7 @@ export function convertToJS(hbs: string) {
   return `${varBlock}${js}`
 }
 
-export { JsErrorTimeout } from "./errors"
+export { JsErrorTimeout, UserScriptError } from "./errors"
 
 export function defaultJSSetup() {
   if (!isBackendService()) {
@@ -473,13 +477,17 @@ export function defaultJSSetup() {
         try {
           result.result = ${js};
         } catch (e) {
-          result.error = e.toString();
+          result.error = e;
         }
 
         result;
       `
 
-      return runInNewContext(js, context, { timeout: 1000 })
+      const result = runInNewContext(js, context, { timeout: 1000 })
+      if (result.error) {
+        throw new UserScriptError(result.error)
+      }
+      return result.result
     })
   } else {
     removeJSRunner()

From f9ccbbe081b447c36ae8b472dc64124833fb8c79 Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 13:11:01 +0100
Subject: [PATCH 04/10] Fix jsRunner.spec.ts.

---
 packages/server/src/jsRunner/tests/jsRunner.spec.ts | 7 ++++---
 packages/server/src/jsRunner/vm/isolated-vm.ts      | 2 +-
 packages/string-templates/src/errors.ts             | 2 +-
 3 files changed, 6 insertions(+), 5 deletions(-)

diff --git a/packages/server/src/jsRunner/tests/jsRunner.spec.ts b/packages/server/src/jsRunner/tests/jsRunner.spec.ts
index 2b9fc08041..7d2df17c1f 100644
--- a/packages/server/src/jsRunner/tests/jsRunner.spec.ts
+++ b/packages/server/src/jsRunner/tests/jsRunner.spec.ts
@@ -41,10 +41,11 @@ describe("jsRunner (using isolated-vm)", () => {
   })
 
   it("should prevent sandbox escape", async () => {
-    const output = await processJS(
-      `return this.constructor.constructor("return process.env")()`
+    await expect(
+      processJS(`return this.constructor.constructor("return process.env")()`)
+    ).rejects.toThrow(
+      "error while running user-supplied JavaScript: ReferenceError: process is not defined"
     )
-    expect(output).toBe("ReferenceError: process is not defined")
   })
 
   describe("helpers", () => {
diff --git a/packages/server/src/jsRunner/vm/isolated-vm.ts b/packages/server/src/jsRunner/vm/isolated-vm.ts
index 9262687925..0a9e93f475 100644
--- a/packages/server/src/jsRunner/vm/isolated-vm.ts
+++ b/packages/server/src/jsRunner/vm/isolated-vm.ts
@@ -22,7 +22,7 @@ class UserScriptError extends Error {
   code = "USER_SCRIPT_ERROR"
   constructor(readonly userScriptError: Error) {
     super(
-      `error while running user-supplied JavaScript: ${userScriptError.message}`,
+      `error while running user-supplied JavaScript: ${userScriptError.toString()}`,
       { cause: userScriptError }
     )
   }
diff --git a/packages/string-templates/src/errors.ts b/packages/string-templates/src/errors.ts
index 4c7cbdb360..d68461561e 100644
--- a/packages/string-templates/src/errors.ts
+++ b/packages/string-templates/src/errors.ts
@@ -7,7 +7,7 @@ export class UserScriptError extends Error {
 
   constructor(readonly userScriptError: Error) {
     super(
-      `error while running user-supplied JavaScript: ${userScriptError.message}`
+      `error while running user-supplied JavaScript: ${userScriptError.toString()}`
     )
   }
 }

From 795b10c4c9145d15c78ae708b51af44de179b924 Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 13:11:35 +0100
Subject: [PATCH 05/10] Fix types in string-templates.

---
 packages/string-templates/src/index.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/string-templates/src/index.ts b/packages/string-templates/src/index.ts
index aceea1da7e..8fd2e7bfc4 100644
--- a/packages/string-templates/src/index.ts
+++ b/packages/string-templates/src/index.ts
@@ -230,7 +230,7 @@ export function processStringSync(
     } else {
       return process(string)
     }
-  } catch (err) {
+  } catch (err: any) {
     if (err.code === "USER_SCRIPT_ERROR") {
       throw err
     }

From 646fc5e6bdde971b5c08b62bb0b529022740f9de Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 15:56:19 +0100
Subject: [PATCH 06/10] Respond to PR comment.

---
 .../bindings/EvaluationSidePanel.svelte       |  3 ++-
 .../server/src/jsRunner/vm/isolated-vm.ts     | 26 +++++--------------
 .../src/utilities/rowProcessor/utils.ts       |  4 +--
 packages/string-templates/src/errors.ts       |  4 +--
 .../src/helpers/javascript.ts                 |  8 +++---
 packages/string-templates/src/index.ts        |  6 ++---
 6 files changed, 18 insertions(+), 33 deletions(-)

diff --git a/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte b/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
index 2c5c1d4587..ffb8f45297 100644
--- a/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
+++ b/packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte
@@ -3,6 +3,7 @@
   import { Icon, ProgressCircle, notifications } from "@budibase/bbui"
   import { copyToClipboard } from "@budibase/bbui/helpers"
   import { fade } from "svelte/transition"
+  import { UserScriptError } from "@budibase/string-templates"
 
   export let expressionResult
   export let expressionError
@@ -15,7 +16,7 @@
   $: highlightedResult = highlight(expressionResult)
 
   const formatError = err => {
-    if (err.code === "USER_SCRIPT_ERROR") {
+    if (err.code === UserScriptError.code) {
       return err.userScriptError.toString()
     }
     return err.toString()
diff --git a/packages/server/src/jsRunner/vm/isolated-vm.ts b/packages/server/src/jsRunner/vm/isolated-vm.ts
index 0a9e93f475..87478a2f8a 100644
--- a/packages/server/src/jsRunner/vm/isolated-vm.ts
+++ b/packages/server/src/jsRunner/vm/isolated-vm.ts
@@ -7,27 +7,13 @@ import querystring from "querystring"
 
 import { BundleType, loadBundle } from "../bundles"
 import { Snippet, VM } from "@budibase/types"
-import { iifeWrapper } from "@budibase/string-templates"
+import {
+  iifeWrapper,
+  JsErrorTimeout,
+  UserScriptError,
+} from "@budibase/string-templates"
 import environment from "../../environment"
 
-class ExecutionTimeoutError extends Error {
-  code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
-  constructor(message: string) {
-    super(message)
-    this.name = "ExecutionTimeoutError"
-  }
-}
-
-class UserScriptError extends Error {
-  code = "USER_SCRIPT_ERROR"
-  constructor(readonly userScriptError: Error) {
-    super(
-      `error while running user-supplied JavaScript: ${userScriptError.toString()}`,
-      { cause: userScriptError }
-    )
-  }
-}
-
 export class IsolatedVM implements VM {
   private isolate: ivm.Isolate
   private vm: ivm.Context
@@ -223,7 +209,7 @@ export class IsolatedVM implements VM {
     if (this.isolateAccumulatedTimeout) {
       const cpuMs = Number(this.isolate.cpuTime) / 1e6
       if (cpuMs > this.isolateAccumulatedTimeout) {
-        throw new ExecutionTimeoutError(
+        throw new JsErrorTimeout(
           `CPU time limit exceeded (${cpuMs}ms > ${this.isolateAccumulatedTimeout}ms)`
         )
       }
diff --git a/packages/server/src/utilities/rowProcessor/utils.ts b/packages/server/src/utilities/rowProcessor/utils.ts
index 3a1ce08ece..29a5de221f 100644
--- a/packages/server/src/utilities/rowProcessor/utils.ts
+++ b/packages/server/src/utilities/rowProcessor/utils.ts
@@ -1,5 +1,5 @@
 import { AutoFieldDefaultNames } from "../../constants"
-import { processStringSync } from "@budibase/string-templates"
+import { processStringSync, UserScriptError } from "@budibase/string-templates"
 import {
   AutoColumnFieldMetadata,
   FieldSchema,
@@ -84,7 +84,7 @@ export async function processFormulas<T extends Row | Row[]>(
               try {
                 return processStringSync(formula, context)
               } catch (err: any) {
-                if (err.code === "USER_SCRIPT_ERROR") {
+                if (err.code === UserScriptError.code) {
                   return err.userScriptError.toString()
                 }
                 throw err
diff --git a/packages/string-templates/src/errors.ts b/packages/string-templates/src/errors.ts
index d68461561e..7a300ac863 100644
--- a/packages/string-templates/src/errors.ts
+++ b/packages/string-templates/src/errors.ts
@@ -1,9 +1,9 @@
 export class JsErrorTimeout extends Error {
-  code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
+  static code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
 }
 
 export class UserScriptError extends Error {
-  code = "USER_SCRIPT_ERROR"
+  static code = "USER_SCRIPT_ERROR"
 
   constructor(readonly userScriptError: Error) {
     super(
diff --git a/packages/string-templates/src/helpers/javascript.ts b/packages/string-templates/src/helpers/javascript.ts
index e1d7f3e8a3..059c8a95f5 100644
--- a/packages/string-templates/src/helpers/javascript.ts
+++ b/packages/string-templates/src/helpers/javascript.ts
@@ -3,6 +3,7 @@ import cloneDeep from "lodash/fp/cloneDeep"
 import { LITERAL_MARKER } from "../helpers/constants"
 import { getJsHelperList } from "./list"
 import { iifeWrapper } from "../iife"
+import { JsErrorTimeout, UserScriptError } from "../errors"
 
 // The method of executing JS scripts depends on the bundle being built.
 // This setter is used in the entrypoint (either index.js or index.mjs).
@@ -94,13 +95,10 @@ export function processJS(handlebars: string, context: any) {
   } catch (error: any) {
     onErrorLog && onErrorLog(error)
 
-    if (error.code === "ERR_SCRIPT_EXECUTION_TIMEOUT") {
+    if (error.code === JsErrorTimeout.code) {
       return "Timed out while executing JS"
     }
-    if (error.name === "ExecutionTimeoutError") {
-      return "Request JS execution limit hit"
-    }
-    if (error.code === "USER_SCRIPT_ERROR") {
+    if (error.code === UserScriptError.code) {
       throw error
     }
     return "Error while executing JS"
diff --git a/packages/string-templates/src/index.ts b/packages/string-templates/src/index.ts
index 8fd2e7bfc4..fe2b4c261c 100644
--- a/packages/string-templates/src/index.ts
+++ b/packages/string-templates/src/index.ts
@@ -231,7 +231,7 @@ export function processStringSync(
       return process(string)
     }
   } catch (err: any) {
-    if (err.code === "USER_SCRIPT_ERROR") {
+    if (err.code === UserScriptError.code) {
       throw err
     }
     return input
@@ -468,7 +468,7 @@ export function defaultJSSetup() {
       }
       createContext(context)
 
-      js = `
+      const wrappedJs = `
         result = {
           result: null,
           error: null,
@@ -483,7 +483,7 @@ export function defaultJSSetup() {
         result;
       `
 
-      const result = runInNewContext(js, context, { timeout: 1000 })
+      const result = runInNewContext(wrappedJs, context, { timeout: 1000 })
       if (result.error) {
         throw new UserScriptError(result.error)
       }

From 03c514be4c6e8effb1ec657282d6c5415eaf5e78 Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 16:16:42 +0100
Subject: [PATCH 07/10] Fix tests.

---
 .../server/src/api/routes/tests/row.spec.ts     | 17 +++++++++--------
 packages/server/src/jsRunner/index.ts           |  4 ++--
 packages/server/src/jsRunner/vm/isolated-vm.ts  | 13 +++++++------
 packages/string-templates/src/errors.ts         | 11 +++++++++--
 .../string-templates/src/helpers/javascript.ts  |  9 ++++++---
 packages/string-templates/src/index.ts          |  2 +-
 6 files changed, 34 insertions(+), 22 deletions(-)

diff --git a/packages/server/src/api/routes/tests/row.spec.ts b/packages/server/src/api/routes/tests/row.spec.ts
index f751942df9..7b590befc0 100644
--- a/packages/server/src/api/routes/tests/row.spec.ts
+++ b/packages/server/src/api/routes/tests/row.spec.ts
@@ -49,6 +49,7 @@ import * as uuid from "uuid"
 import { Knex } from "knex"
 import { InternalTables } from "../../../db/utils"
 import { withEnv } from "../../../environment"
+import { JsTimeoutError } from "@budibase/string-templates/src/errors"
 
 const timestamp = new Date("2023-01-26T11:48:57.597Z").toISOString()
 tk.freeze(timestamp)
@@ -76,13 +77,13 @@ async function waitForEvent(
 }
 
 describe.each([
-  ["lucene", undefined],
+  //  ["lucene", undefined],
   ["sqs", undefined],
-  [DatabaseName.POSTGRES, getDatasource(DatabaseName.POSTGRES)],
-  [DatabaseName.MYSQL, getDatasource(DatabaseName.MYSQL)],
-  [DatabaseName.SQL_SERVER, getDatasource(DatabaseName.SQL_SERVER)],
-  [DatabaseName.MARIADB, getDatasource(DatabaseName.MARIADB)],
-  [DatabaseName.ORACLE, getDatasource(DatabaseName.ORACLE)],
+  // [DatabaseName.POSTGRES, getDatasource(DatabaseName.POSTGRES)],
+  // [DatabaseName.MYSQL, getDatasource(DatabaseName.MYSQL)],
+  // [DatabaseName.SQL_SERVER, getDatasource(DatabaseName.SQL_SERVER)],
+  // [DatabaseName.MARIADB, getDatasource(DatabaseName.MARIADB)],
+  // [DatabaseName.ORACLE, getDatasource(DatabaseName.ORACLE)],
 ])("/rows (%s)", (providerType, dsProvider) => {
   const isInternal = dsProvider === undefined
   const isLucene = providerType === "lucene"
@@ -3013,7 +3014,7 @@ describe.each([
             let i = 0
             for (; i < 10; i++) {
               const row = rows[i]
-              if (row.formula !== "Timed out while executing JS") {
+              if (row.formula !== JsTimeoutError.message) {
                 break
               }
             }
@@ -3027,7 +3028,7 @@ describe.each([
             for (; i < 10; i++) {
               const row = rows[i]
               expect(row.text).toBe("foo")
-              expect(row.formula).toBe("Request JS execution limit hit")
+              expect(row.formula).toStartWith("CPU time limit exceeded ")
             }
           }
         }
diff --git a/packages/server/src/jsRunner/index.ts b/packages/server/src/jsRunner/index.ts
index ccfca7cb4c..e17529a687 100644
--- a/packages/server/src/jsRunner/index.ts
+++ b/packages/server/src/jsRunner/index.ts
@@ -1,7 +1,7 @@
 import { serializeError } from "serialize-error"
 import env from "../environment"
 import {
-  JsErrorTimeout,
+  JsTimeoutError,
   setJSRunner,
   setOnErrorLog,
 } from "@budibase/string-templates"
@@ -40,7 +40,7 @@ export function init() {
         return vm.withContext(rest, () => vm.execute(js))
       } catch (error: any) {
         if (error.message === "Script execution timed out.") {
-          throw new JsErrorTimeout()
+          throw new JsTimeoutError()
         }
         throw error
       }
diff --git a/packages/server/src/jsRunner/vm/isolated-vm.ts b/packages/server/src/jsRunner/vm/isolated-vm.ts
index 87478a2f8a..b8ed90aa23 100644
--- a/packages/server/src/jsRunner/vm/isolated-vm.ts
+++ b/packages/server/src/jsRunner/vm/isolated-vm.ts
@@ -7,13 +7,14 @@ import querystring from "querystring"
 
 import { BundleType, loadBundle } from "../bundles"
 import { Snippet, VM } from "@budibase/types"
-import {
-  iifeWrapper,
-  JsErrorTimeout,
-  UserScriptError,
-} from "@budibase/string-templates"
+import { iifeWrapper, UserScriptError } from "@budibase/string-templates"
 import environment from "../../environment"
 
+export class JsRequestTimeoutError extends Error {
+  static code = "JS_REQUEST_TIMEOUT_ERROR"
+  code = JsRequestTimeoutError.code
+}
+
 export class IsolatedVM implements VM {
   private isolate: ivm.Isolate
   private vm: ivm.Context
@@ -209,7 +210,7 @@ export class IsolatedVM implements VM {
     if (this.isolateAccumulatedTimeout) {
       const cpuMs = Number(this.isolate.cpuTime) / 1e6
       if (cpuMs > this.isolateAccumulatedTimeout) {
-        throw new JsErrorTimeout(
+        throw new JsRequestTimeoutError(
           `CPU time limit exceeded (${cpuMs}ms > ${this.isolateAccumulatedTimeout}ms)`
         )
       }
diff --git a/packages/string-templates/src/errors.ts b/packages/string-templates/src/errors.ts
index 7a300ac863..77526c1b96 100644
--- a/packages/string-templates/src/errors.ts
+++ b/packages/string-templates/src/errors.ts
@@ -1,9 +1,16 @@
-export class JsErrorTimeout extends Error {
-  static code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
+export class JsTimeoutError extends Error {
+  static message = "Timed out while executing JS"
+  static code = "JS_TIMEOUT_ERROR"
+  code: string = JsTimeoutError.code
+
+  constructor() {
+    super(JsTimeoutError.message)
+  }
 }
 
 export class UserScriptError extends Error {
   static code = "USER_SCRIPT_ERROR"
+  code: string = UserScriptError.code
 
   constructor(readonly userScriptError: Error) {
     super(
diff --git a/packages/string-templates/src/helpers/javascript.ts b/packages/string-templates/src/helpers/javascript.ts
index 059c8a95f5..879cd29fa6 100644
--- a/packages/string-templates/src/helpers/javascript.ts
+++ b/packages/string-templates/src/helpers/javascript.ts
@@ -3,7 +3,7 @@ import cloneDeep from "lodash/fp/cloneDeep"
 import { LITERAL_MARKER } from "../helpers/constants"
 import { getJsHelperList } from "./list"
 import { iifeWrapper } from "../iife"
-import { JsErrorTimeout, UserScriptError } from "../errors"
+import { JsTimeoutError, UserScriptError } from "../errors"
 
 // The method of executing JS scripts depends on the bundle being built.
 // This setter is used in the entrypoint (either index.js or index.mjs).
@@ -95,8 +95,11 @@ export function processJS(handlebars: string, context: any) {
   } catch (error: any) {
     onErrorLog && onErrorLog(error)
 
-    if (error.code === JsErrorTimeout.code) {
-      return "Timed out while executing JS"
+    if (error.code === "JS_REQUEST_TIMEOUT_ERROR") {
+      return error.message
+    }
+    if (error.code === JsTimeoutError.code) {
+      return JsTimeoutError.message
     }
     if (error.code === UserScriptError.code) {
       throw error
diff --git a/packages/string-templates/src/index.ts b/packages/string-templates/src/index.ts
index fe2b4c261c..0f5326374f 100644
--- a/packages/string-templates/src/index.ts
+++ b/packages/string-templates/src/index.ts
@@ -452,7 +452,7 @@ export function convertToJS(hbs: string) {
   return `${varBlock}${js}`
 }
 
-export { JsErrorTimeout, UserScriptError } from "./errors"
+export { JsTimeoutError, UserScriptError } from "./errors"
 
 export function defaultJSSetup() {
   if (!isBackendService()) {

From 15a30b1d9ef30b14770ef8ab2ade298bcdee98ab Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Thu, 3 Oct 2024 16:32:14 +0100
Subject: [PATCH 08/10] Fix yet more tests.

---
 .../server/src/api/routes/tests/row.spec.ts   | 14 +++++------
 .../src/helpers/javascript.ts                 | 23 +++++++++++++++++++
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/packages/server/src/api/routes/tests/row.spec.ts b/packages/server/src/api/routes/tests/row.spec.ts
index 7b590befc0..5222069460 100644
--- a/packages/server/src/api/routes/tests/row.spec.ts
+++ b/packages/server/src/api/routes/tests/row.spec.ts
@@ -49,7 +49,7 @@ import * as uuid from "uuid"
 import { Knex } from "knex"
 import { InternalTables } from "../../../db/utils"
 import { withEnv } from "../../../environment"
-import { JsTimeoutError } from "@budibase/string-templates/src/errors"
+import { JsTimeoutError } from "@budibase/string-templates"
 
 const timestamp = new Date("2023-01-26T11:48:57.597Z").toISOString()
 tk.freeze(timestamp)
@@ -77,13 +77,13 @@ async function waitForEvent(
 }
 
 describe.each([
-  //  ["lucene", undefined],
+  ["lucene", undefined],
   ["sqs", undefined],
-  // [DatabaseName.POSTGRES, getDatasource(DatabaseName.POSTGRES)],
-  // [DatabaseName.MYSQL, getDatasource(DatabaseName.MYSQL)],
-  // [DatabaseName.SQL_SERVER, getDatasource(DatabaseName.SQL_SERVER)],
-  // [DatabaseName.MARIADB, getDatasource(DatabaseName.MARIADB)],
-  // [DatabaseName.ORACLE, getDatasource(DatabaseName.ORACLE)],
+  [DatabaseName.POSTGRES, getDatasource(DatabaseName.POSTGRES)],
+  [DatabaseName.MYSQL, getDatasource(DatabaseName.MYSQL)],
+  [DatabaseName.SQL_SERVER, getDatasource(DatabaseName.SQL_SERVER)],
+  [DatabaseName.MARIADB, getDatasource(DatabaseName.MARIADB)],
+  [DatabaseName.ORACLE, getDatasource(DatabaseName.ORACLE)],
 ])("/rows (%s)", (providerType, dsProvider) => {
   const isInternal = dsProvider === undefined
   const isLucene = providerType === "lucene"
diff --git a/packages/string-templates/src/helpers/javascript.ts b/packages/string-templates/src/helpers/javascript.ts
index 879cd29fa6..d5183ef3ed 100644
--- a/packages/string-templates/src/helpers/javascript.ts
+++ b/packages/string-templates/src/helpers/javascript.ts
@@ -95,15 +95,38 @@ export function processJS(handlebars: string, context: any) {
   } catch (error: any) {
     onErrorLog && onErrorLog(error)
 
+    // The error handling below is quite messy, because it has fallen to
+    // string-templates to handle a variety of types of error specific to usages
+    // above it in the stack. It would be nice some day to refactor this to
+    // allow each user of processStringSync to handle errors in the way they see
+    // fit.
+
+    // This is to catch the error vm.runInNewContext() throws when the timeout
+    // is exceeded.
+    if (error.code === "ERR_SCRIPT_EXECUTION_TIMEOUT") {
+      return "Timed out while executing JS"
+    }
+
+    // This is to catch the JsRequestTimeoutError we throw when we detect a
+    // timeout across an entire request in the backend. We use a magic string
+    // because we can't import from the backend into string-templates.
     if (error.code === "JS_REQUEST_TIMEOUT_ERROR") {
       return error.message
     }
+
+    // This is to catch the JsTimeoutError we throw when we detect a timeout in
+    // a single JS execution.
     if (error.code === JsTimeoutError.code) {
       return JsTimeoutError.message
     }
+
+    // This is to catch the error that happens if a user-supplied JS script
+    // throws for reasons introduced by the user.
     if (error.code === UserScriptError.code) {
       throw error
     }
+
+    // If all else fails, generic error message.
     return "Error while executing JS"
   }
 }

From 831c81a99c3aa701d817ffa878d67f3073560497 Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Fri, 4 Oct 2024 09:31:42 +0100
Subject: [PATCH 09/10] Fix automation tests.

---
 packages/server/src/api/controllers/script.ts | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/packages/server/src/api/controllers/script.ts b/packages/server/src/api/controllers/script.ts
index 4317f5fcde..0565b30f74 100644
--- a/packages/server/src/api/controllers/script.ts
+++ b/packages/server/src/api/controllers/script.ts
@@ -1,11 +1,18 @@
 import { Ctx } from "@budibase/types"
 import { IsolatedVM } from "../../jsRunner/vm"
-import { iifeWrapper } from "@budibase/string-templates"
+import { iifeWrapper, UserScriptError } from "@budibase/string-templates"
 
 export async function execute(ctx: Ctx) {
   const { script, context } = ctx.request.body
   const vm = new IsolatedVM()
-  ctx.body = vm.withContext(context, () => vm.execute(iifeWrapper(script)))
+  try {
+    ctx.body = vm.withContext(context, () => vm.execute(iifeWrapper(script)))
+  } catch (err: any) {
+    if (err.code === UserScriptError.code) {
+      throw err.userScriptError
+    }
+    throw err
+  }
 }
 
 export async function save(ctx: Ctx) {

From 28e6a039292e65b1df9347671999aa858253747c Mon Sep 17 00:00:00 2001
From: Sam Rose <hello@samwho.dev>
Date: Fri, 4 Oct 2024 10:32:33 +0100
Subject: [PATCH 10/10] Include syntax errors in processJS

---
 packages/string-templates/src/helpers/javascript.ts | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/packages/string-templates/src/helpers/javascript.ts b/packages/string-templates/src/helpers/javascript.ts
index d5183ef3ed..ed8d4ad6d7 100644
--- a/packages/string-templates/src/helpers/javascript.ts
+++ b/packages/string-templates/src/helpers/javascript.ts
@@ -126,7 +126,10 @@ export function processJS(handlebars: string, context: any) {
       throw error
     }
 
-    // If all else fails, generic error message.
+    if (error.name === "SyntaxError") {
+      return error.toString()
+    }
+
     return "Error while executing JS"
   }
 }