Correctly handle JS nullish values by removing forced fallback value of HBS helper

packages/string-templates/src/helpers/Helper.js

@@ -1,14 +1,20 @@
 class Helper {
-  constructor(name, fn) {
+  constructor(name, fn, useValueFallback = true) {
     this.name = name
     this.fn = fn
+    this.useValueFallback = useValueFallback
   }
 
   register(handlebars) {
     // wrap the function so that no helper can cause handlebars to break
     handlebars.registerHelper(this.name, (value, info) => {
-      const context = info?.data?.root
+      const context = info?.data?.root || {}
-      return this.fn(value, context || {}) || value
+      const result = this.fn(value, context)
+      if (result == null) {
+        return this.useValueFallback ? value : null
+      } else {
+        return result
+      }
     })
   }
 

packages/string-templates/src/helpers/index.js

@@ -19,7 +19,7 @@ const HELPERS = [
     return new SafeString(JSON.stringify(value))
   }),
   // javascript helper
-  new Helper(HelperFunctionNames.JS, processJS),
+  new Helper(HelperFunctionNames.JS, processJS, false),
   // this help is applied to all statements
   new Helper(HelperFunctionNames.ALL, value => {
     if (

packages/string-templates/src/helpers/javascript.js

@@ -36,11 +36,7 @@ module.exports.processJS = (handlebars, context) => {
 
     // Create a sandbox with out context and run the JS
     vm.createContext(sandboxContext)
-    const result = vm.runInNewContext(js, sandboxContext)
+    return vm.runInNewContext(js, sandboxContext)
-    if (result == null || result === "") {
-      return " "
-    }
-    return result
   } catch (error) {
     return "Error while executing JS"
   }