diff --git a/app/plugin/TableOperations.ts b/app/plugin/TableOperations.ts
index 3deb4eb5..9ca64d09 100644
--- a/app/plugin/TableOperations.ts
+++ b/app/plugin/TableOperations.ts
@@ -18,8 +18,7 @@ export interface TableOperations {
   /**
    * Delete a record or records.
    */
-  destroy(recordId: Types.RecordId): Promise<Types.RecordId>;
-  destroy(recordIds: Types.RecordId[]): Promise<Types.RecordId[]>;
+  destroy(recordIds: Types.RecordId|Types.RecordId[]): Promise<void>;
 
   /**
    * Add or update a record or records.
diff --git a/app/plugin/TableOperationsImpl.ts b/app/plugin/TableOperationsImpl.ts
index e569a73c..214a5a89 100644
--- a/app/plugin/TableOperationsImpl.ts
+++ b/app/plugin/TableOperationsImpl.ts
@@ -67,15 +67,12 @@ export class TableOperationsImpl implements TableOperations {
     });
   }
 
-  public destroy(recordId: Types.RecordId): Promise<Types.RecordId>;
-  public destroy(recordIds: Types.RecordId[]): Promise<Types.RecordId[]>;
-  public async destroy(recordIdOrRecordIds: Types.RecordId|Types.RecordId[]): Promise<Types.RecordId|Types.RecordId[]> {
-    return withRecords(recordIdOrRecordIds, async (recordIds) => {
+  public async destroy(recordIdOrRecordIds: Types.RecordId|Types.RecordId[]): Promise<void> {
+    await withRecords(recordIdOrRecordIds, async (recordIds) => {
       const tableId = await this._platform.getTableId();
       const actions = [['BulkRemoveRecord', tableId, recordIds]];
-      const sandboxRes = await this._applyUserActions(
-        tableId, [], actions);
-      return sandboxRes.retValues[0];
+      await this._applyUserActions(tableId, [], actions);
+      return [];
     });
   }
 
diff --git a/app/plugin/grist-plugin-api.ts b/app/plugin/grist-plugin-api.ts
index dd17c180..d52c662d 100644
--- a/app/plugin/grist-plugin-api.ts
+++ b/app/plugin/grist-plugin-api.ts
@@ -216,13 +216,13 @@ async function getMappingsIfChanged(data: any): Promise<WidgetColumnMap|null> {
  * Returns null if not all required columns were mapped or not widget doesn't support
  * custom column mapping.
  */
-export function mapColumnNames(data: any, options: {
+export function mapColumnNames(data: any, options?: {
   columns?: ColumnsToMap
   mappings?: WidgetColumnMap|null,
   reverse?: boolean,
 }) {
   options = {columns: _columnsToMap, mappings: _mappingsCache, reverse: false, ...options};
-  // If not column configuration was requested or
+  // If no column configuration was requested or
   // table has no rows, return original data.
   if (!options.columns) {
     return data;
@@ -246,8 +246,8 @@ export function mapColumnNames(data: any, options: {
   function isOptional(col: string) {
     return Boolean(
       // Columns passed as strings are required.
-      !options.columns?.includes(col)
-      && options.columns?.find(c => typeof c === 'object' && c?.name === col && c.optional)
+      !options!.columns?.includes(col)
+      && options!.columns?.find(c => typeof c === 'object' && c?.name === col && c.optional)
     );
   }
   // For each widget column in mapping.
@@ -292,7 +292,7 @@ export function mapColumnNames(data: any, options: {
  * original table in a widget with column mappings. As for mapColumnNames(),
  * we don't attempt to do these transformations automatically.
  */
-export function mapColumnNamesBack(data: any, options: {
+export function mapColumnNamesBack(data: any, options?: {
   columns?: ColumnsToMap
   mappings?: WidgetColumnMap|null,
 }) {
@@ -320,10 +320,10 @@ export function onRecord(callback: (data: RowRecord | null, mappings: WidgetColu
  * For custom widgets, add a handler that will be called whenever the
  * new (blank) row is selected.
  */
-export function onNewRecord(callback: () => unknown) {
+export function onNewRecord(callback: (mappings: WidgetColumnMap | null) => unknown) {
   on('message', async function(msg) {
     if (msg.tableId && msg.rowId === 'new') {
-      callback();
+      callback(await getMappingsIfChanged(msg));
     }
   });
 }
diff --git a/app/server/lib/DocApi.ts b/app/server/lib/DocApi.ts
index c7d6b44f..3b5b0492 100644
--- a/app/server/lib/DocApi.ts
+++ b/app/server/lib/DocApi.ts
@@ -298,7 +298,8 @@ export class DocWorkerApi {
     this._app.post('/api/docs/:docId/tables/:tableId/data/delete', canEdit, withDoc(async (activeDoc, req, res) => {
       const rowIds = req.body;
       const op = getTableOperations(req, activeDoc);
-      res.json(await op.destroy(rowIds));
+      await op.destroy(rowIds);
+      res.json(null);
     }));
 
     // Download full document