facebook/lexical · warning

console.warn(error)

Error message

console.warn(error)

What it means

defaultOnWarn is Lexical's default handler for recoverable problems routed through the editor's onWarn callback. In development (__DEV__) it throws to surface issues loudly; in production it only logs via console.warn so user-facing apps never crash on a warning.

Source

Thrown at packages/lexical/src/LexicalEditor.ts:517

};

export type Transform<T extends LexicalNode> = (node: T) => void;

export type ErrorHandler = (error: Error) => void;

/**
 * Default {@link CreateEditorArgs.onWarn} handler. Used for recoverable,
 * warn-level conditions (e.g. the update-recursion guard tripping) that the
 * editor has already recovered from. Throws in development so the condition is
 * impossible to miss, and only `console.warn`s in production so it is not
 * reported as a fatal error. Embedders can override this via `onWarn` to route
 * the condition to their own telemetry at warn severity.
 */
function defaultOnWarn(error: Error): void {
  if (__DEV__) {
    throw error;
  }
  console.warn(error);
}

export type MutationListeners = Map<MutationListener, Set<Klass<LexicalNode>>>;

export type MutatedNodes = Map<Klass<LexicalNode>, Map<NodeKey, NodeMutation>>;

export type NodeMutation = 'created' | 'updated' | 'destroyed';

export interface MutationListenerOptions {
  /**
   * Skip the initial call of the listener with pre-existing DOM nodes.
   *
   * The default was previously true for backwards compatibility with <= 0.16.1
   * but this default has been changed to false as of 0.21.0.
   */
  skipInitialization?: boolean;
}

View on GitHub (pinned to 76a22dcba9)

Solutions

1. Fix the underlying condition named by the thrown error (dev throws carry the full message).
2. Supply onWarn in the editor config to route warnings to logging/telemetry instead of throwing: onWarn: (error) => console.error(error) or your reporter.
3. Suppress noise in tests by installing a permissive onWarn in test editors.
4. Only rely on prod behavior (console.warn) for end-user builds; do not treat prod warn silence as health.

Example fix

// before
const editor = createEditor({ namespace: 'app' });
// after
const editor = createEditor({
  namespace: 'app',
  onWarn: (error) => myTelemetry.warn(error.message),
});

null

null

try {
  runEditorOperation(editor);
} catch (e) {
  if (__DEV__ && e instanceof Error && e.message.includes('Lexical')) {
    myTelemetry.warn('Lexical dev warning thrown', e.message);
  } else { throw e; }
}

When it happens

Trigger: An editor warning is emitted and no custom onWarn was supplied to createEditor; in dev builds this propagates the error as a thrown exception at the point of detection.

Common situations: Seeing unexpected throws in dev mode for recoverable conditions; wanting warnings collected in telemetry instead of thrown; CI runs where dev-mode throws fail tests for benign issues.

AI-assisted analysis of facebook/lexical@76a22dcba9 (2026-08-31). Data as JSON: /api/errors/3764b35359a491be. Report an issue: GitHub.