Ported source selection unknown error test

__tests__/frontend-playwright/source-selection-unknown-error.spec.ts

@@ -0,0 +1,28 @@
+import { expect, test } from "@playwright/test";
+
+import { setup } from "../test-utils-playwright/stub-endpoints";
+
+test("handles raw errors in source folder selection gracefully", async ({
+  page,
+}) => {
+  await page.goto("/");
+  await setup(page);
+
+  await page.evaluate(() => {
+    window._endpointStubs.listSharedDrives = [
+      {
+        status: "success",
+        value: { status: "error", type: "unknown" },
+      },
+    ];
+  });
+
+  await expect(
+    page.getByText("Shared drive mover", { exact: true }),
+  ).toBeVisible();
+  await page.getByText("Continue").click();
+  await expect(
+    page.getByText("An error occurred", { exact: true }),
+  ).toBeVisible();
+  await expect(page.getByText("An unknown error occurred")).toBeVisible();
+});