fix(desktop): show notebook not empty delete message

apps/web/src/lib/notebook-delete.test.mjs

@@ -1,5 +1,11 @@
 import { describe, expect, test } from "bun:test";
-import { notebookDeleteIdsFromPayload, notebooksBlockedByPendingDeletes } from "./notebook-delete.ts";
+import { isNotebookNotEmptyError, notebookDeleteIdsFromPayload, notebooksBlockedByPendingDeletes } from "./notebook-delete.ts";
+
+test("recognizes a notebook with notes through Electron's IPC error wrapper", () => {
+  expect(isNotebookNotEmptyError(new Error("notebook_not_empty"))).toBe(true);
+  expect(isNotebookNotEmptyError(new Error("Error invoking remote method 'desktop:sidecar-request': Error: notebook_not_empty"))).toBe(true);
+  expect(isNotebookNotEmptyError(new Error("Error invoking remote method 'desktop:sidecar-request': Error: database is busy"))).toBe(false);
+});
 
 describe("notebook delete ids", () => {
   test("uses the ordered descendant list and falls back to the single id", () => {

apps/web/src/lib/notebook-delete.ts

@@ -12,7 +12,9 @@ export const isNotebookNotEmptyError = (error: unknown) => {
   if (typeof error === "object" && error !== null && "code" in error && (error as { code?: unknown }).code === "notebook_not_empty") {
     return true;
   }
-  return error instanceof Error && error.message === "notebook_not_empty";
+  // Electron prefixes errors thrown by the sidecar IPC handler, for example:
+  // Error invoking remote method 'desktop:sidecar-request': Error: notebook_not_empty
+  return error instanceof Error && /(?:^|:\s*)notebook_not_empty$/.test(error.message.trim());
 };
 
 export const notebookDeleteIdsFromPayload = (