How to determine app crash in NextJs/Sentry?

[janglewood]

I have NextJs application with Sentry installed. But I can't find a way to recognize which errors causes app crashing. For example: I'm showing /500 page everytime when errors occurs during the render process and I want to see only these errors on Sentry dashboard. Is it possible at all?

[AbhiPrasad]

@janglewood could you attach a tag to those errors? Via Sentry.setTag when those render errors are caught? you should be able to add this in your error.js/global-error.js files: https://nextjs.org/docs/app/building-your-application/routing/error-handling

[janglewood]

@AbhiPrasad Thanks for the response!
I'm using pages routing so I don't have _error.js file but I'm using 500.js page.
I'm trying to set tags inside beforeCapture function but seems like this function is never executed. Could u help me with that?

const onPageError = (scope: Scope, _: Error | null, stack: string | null) => {
        console.log('-----', scope, '---', stack);
        scope.setTags({ [router.pathname === '/500' ? 'CRASH' : ErrorLevelTag]: ErrorLevel.Page });
        scope.setTag('path', router.pathname);
        scope.setExtra('data', { stack });
        Sentry.setExtra('path', { data: router.pathname });
    };
    
return (
  <ErrorBoundary
       beforeCapture={onPageError}
       fallback={({ eventId }) => <InternalServerError eventId={eventId} />}
   >                                 
       <Component {...pageProps} />            
   </ErrorBoundary>
)

[AbhiPrasad]

I'm trying to set tags inside beforeCapture function but seems like this function is never executed. Could u help me with that?

are you running in development mode? Error boundaries will rethrow errors in dev mode, so they don't captured properly. Make sure you test in production mode.

[JorgeSivil]

I'm also interested in knowing how to detect app crashes since those are obviously higher priority than normal console.error