polish(theme): better error messages on navbar item rendering failures + ErrorCauseBoundary API (#8735)

Co-authored-by: sebastienlorber <lorber.sebastien@gmail.com>

packages/docusaurus-utils-common/src/__tests__/errorUtils.test.ts

@@ -0,0 +1,26 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+import {getErrorCausalChain} from '../errorUtils';
+
+describe('getErrorCausalChain', () => {
+  it('works for simple error', () => {
+    const error = new Error('msg');
+    expect(getErrorCausalChain(error)).toEqual([error]);
+  });
+
+  it('works for nested errors', () => {
+    const error = new Error('msg', {
+      cause: new Error('msg', {cause: new Error('msg')}),
+    });
+    expect(getErrorCausalChain(error)).toEqual([
+      error,
+      error.cause,
+      (error.cause as Error).cause,
+    ]);
+  });
+});

packages/docusaurus-utils-common/src/errorUtils.ts

@@ -0,0 +1,14 @@
+/**
+ * Copyright (c) Facebook, Inc. and its affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+type CausalChain = [Error, ...Error[]];
+
+export function getErrorCausalChain(error: Error): CausalChain {
+  if (error.cause) {
+    return [error, ...getErrorCausalChain(error.cause as Error)];
+  }
+  return [error];
+}

packages/docusaurus-utils-common/src/index.ts

@@ -10,3 +10,4 @@ export {
   default as applyTrailingSlash,
   type ApplyTrailingSlashParams,
 } from './applyTrailingSlash';
+export {getErrorCausalChain} from './errorUtils';