[extensions] Add disable command (#7001)

Co-authored-by: gemini-code-assist[bot] <176961590+gemini-code-assist[bot]@users.noreply.github.com>

packages/cli/src/utils/errors.ts

@@ -0,0 +1,12 @@
+/**
+ * @license
+ * Copyright 2025 Google LLC
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+export function getErrorMessage(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message;
+  }
+  return String(error);
+}