Fix tabs editor id

src/vs/workbench/api/browser/mainThreadEditorTabs.ts

@@ -8,6 +8,7 @@ import { URI } from 'vs/base/common/uri';
 import { ExtHostContext, IExtHostEditorTabsShape, IExtHostContext, MainContext, IEditorTabDto } from 'vs/workbench/api/common/extHost.protocol';
 import { extHostNamedCustomer } from 'vs/workbench/api/common/extHostCustomers';
 import { EditorResourceAccessor, SideBySideEditor } from 'vs/workbench/common/editor';
+import { DiffEditorInput } from 'vs/workbench/common/editor/diffEditorInput';
 import { EditorInput } from 'vs/workbench/common/editor/editorInput';
 import { SideBySideEditorInput } from 'vs/workbench/common/editor/sideBySideEditorInput';
 import { editorGroupToColumn } from 'vs/workbench/services/editor/common/editorGroupColumn';
@@ -41,11 +42,12 @@ export class MainThreadEditorTabs {
 	}
 
 	private _buildTabObject(editor: EditorInput, group: IEditorGroup): IEditorTabDto {
+		const editorId = editor instanceof DiffEditorInput ? 'diff' : editor instanceof SideBySideEditorInput ? 'sideBySide' : editor.editorId;
 		const tab: IEditorTabDto = {
 			viewColumn: editorGroupToColumn(this._editorGroupsService, group),
 			label: editor.getName(),
 			resource: editor instanceof SideBySideEditorInput ? EditorResourceAccessor.getCanonicalUri(editor, { supportSideBySide: SideBySideEditor.PRIMARY }) : EditorResourceAccessor.getCanonicalUri(editor),
-			editorId: editor instanceof SideBySideEditorInput ? editor.primary.editorId ?? editor.editorId : editor.editorId,
+			editorId,
 			additionalResourcesAndViewIds: [],
 			isActive: (this._editorGroupsService.activeGroup === group) && group.isActive(editor)
 		};