Error Boundaries in React

If a component throws an error, the whole React tree unmounts. The user sees a blank page. ### Error Boundary A class component (still needed for this!) that implements `componentDidCatch`. Wrap your app: `<ErrorBoundary fallback={<ErrorPage />}><App /></ErrorBoundary>` Better yet, wrap individual widgets. If the "Comments" widget crashes, the rest of the blog post should still be visible.