diff --git a/packages/frontend-core/src/components/grid/stores/datasource.ts b/packages/frontend-core/src/components/grid/stores/datasource.ts
index 472f598299..6b4fb8dc52 100644
--- a/packages/frontend-core/src/components/grid/stores/datasource.ts
+++ b/packages/frontend-core/src/components/grid/stores/datasource.ts
@@ -19,7 +19,7 @@ import { DatasourceActions } from "./datasources"
 interface DatasourceStore {
   definition: Writable<UIDatasource>
   schemaMutations: Writable<Record<string, UIFieldMutation>>
-  subSchemaMutations: Writable<Record<string, UIFieldMutation>>
+  subSchemaMutations: Writable<Record<string, Record<string, UIFieldMutation>>>
 }
 
 interface DerivedDatasourceStore {
@@ -197,7 +197,7 @@ export const createActions = (context: StoreContext): ActionDatasourceStore => {
     // Update server
     if (get(config).canSaveSchema) {
       try {
-        await getAPI()?.actions.saveDefinition(newDefinition)
+        await getAPI()?.actions.saveDefinition(newDefinition as never)
 
         // Broadcast change so external state can be updated, as this change
         // will not be received by the builder websocket because we caused it
@@ -277,15 +277,15 @@ export const createActions = (context: StoreContext): ActionDatasourceStore => {
     const $definition = get(definition)
     const $schemaMutations = get(schemaMutations)
     const $subSchemaMutations = get(subSchemaMutations)
-    const $schema = get(schema)
-    let newSchema = {}
+    const $schema = get(schema) || {}
+    let newSchema: Record<string, UIFieldSchema> = {}
 
     // Build new updated datasource schema
     Object.keys($schema).forEach(column => {
       newSchema[column] = {
         ...$schema[column],
         ...$schemaMutations[column],
-      }
+      } as UIFieldSchema // TODO
       if ($subSchemaMutations[column]) {
         newSchema[column].columns ??= {}
         for (const fieldName of Object.keys($subSchemaMutations[column])) {
diff --git a/packages/frontend-core/src/components/grid/stores/datasources/index.ts b/packages/frontend-core/src/components/grid/stores/datasources/index.ts
index a1ade22317..4c3ffc7a74 100644
--- a/packages/frontend-core/src/components/grid/stores/datasources/index.ts
+++ b/packages/frontend-core/src/components/grid/stores/datasources/index.ts
@@ -12,7 +12,7 @@ export interface DatasourceActions<
   saveDefinition: (newDefinition: TSaveDefinitionRequest) => Promise<void>
   addRow: (row: SaveRowRequest) => Promise<Row | void>
   updateRow: (row: SaveRowRequest) => Promise<Row | void>
-  deleteRows: (rows: (string | Row)[]) => Promise<void>
+  deleteRows: (rows: Row[]) => Promise<void>
   getRow: (id: string) => Promise<Row | void>
   isDatasourceValid: (datasource: UIDatasource) => boolean | void
   canUseColumn: (name: string) => boolean | void
diff --git a/packages/frontend-core/src/components/grid/stores/datasources/nonPlus.ts b/packages/frontend-core/src/components/grid/stores/datasources/nonPlus.ts
index 2ea5a05a0e..65fc6d8696 100644
--- a/packages/frontend-core/src/components/grid/stores/datasources/nonPlus.ts
+++ b/packages/frontend-core/src/components/grid/stores/datasources/nonPlus.ts
@@ -5,7 +5,7 @@ import { DatasourceActions } from "."
 
 interface NonPlusActions {
   nonPlus: {
-    actions: DatasourceActions<never>
+    actions: DatasourceActions
   }
 }
 
diff --git a/packages/frontend-core/src/components/grid/stores/datasources/table.ts b/packages/frontend-core/src/components/grid/stores/datasources/table.ts
index 9f1a490306..5f3d27159e 100644
--- a/packages/frontend-core/src/components/grid/stores/datasources/table.ts
+++ b/packages/frontend-core/src/components/grid/stores/datasources/table.ts
@@ -34,7 +34,7 @@ export const createActions = (context: StoreContext): TableActions => {
     return await API.saveRow(row, SuppressErrors)
   }
 
-  const deleteRows = async (rows: (string | Row)[]) => {
+  const deleteRows = async (rows: Row[]) => {
     await API.deleteRows(get(datasource).tableId, rows)
   }
 
diff --git a/packages/frontend-core/src/components/grid/stores/datasources/viewV2.ts b/packages/frontend-core/src/components/grid/stores/datasources/viewV2.ts
index 70a83b4594..edafd94d6f 100644
--- a/packages/frontend-core/src/components/grid/stores/datasources/viewV2.ts
+++ b/packages/frontend-core/src/components/grid/stores/datasources/viewV2.ts
@@ -39,7 +39,7 @@ export const createActions = (context: StoreContext): ViewActions => {
     }
   }
 
-  const deleteRows = async (rows: (string | Row)[]) => {
+  const deleteRows = async (rows: Row[]) => {
     await API.deleteRows(get(datasource).id, rows)
   }