in prod it will be console.error'd if it was a recoverable client error, or a generic error page if it was not recoverable

Sorry for my misunderstanding, but what recoverable means?

recoverable means the page can still be rendered, i.e. your react component still returns something to be displayed normally. usually this means you throw an error in an event handler or useEffect – it affects the event handling but not the component itself

irrecoverable means you throw during the component rendering so react cannot render the component anymore, example:

function Component() {
  const [isErrored, setIsErrored] = useState(false);
  if (isErrored) throw new Error();
  return <button onClick={() => setIsErrored(true)}>Click me</button>;
}

"Cannot read properties of undefined" can be thrown during server/client component rendering (irrecoverable) or during event handlers/useEffect (recoverable)

I see, i'll try to look more into this topic, thank you!