Silently catched error in _app.js getInitialProps

[znarf]

Bug report

Describe the bug

When an error is thrown in _app.js getInitialProps on the client side, the error is silently catched and navigation is broken without any error output.

Why it's a problem? As a developer, if you unfortunately generate an error in _app.js getInitialProps, you suddenly have a broken navigation and have no idea what's happening and where to look at.

To Reproduce

1. Go to https://app-getinitialprops-silent-error-gbvspsorhf.now.sh/
2. Click on 'Say Hello?'
3. Not navigating to /hello, no error output.

Expected behavior

Navigating to /hello OR error output.

Source

https://github.com/opencollective/next-issues/tree/master/app-getInitialProps-silent-error

[timneutkens]

The reason this happens is that when an error is throw in a normal page, we try to render the error page, but the error page also depends on getInitialProps being executed, as you can see here: https://github.com/zeit/next.js/blob/canary/lib/router/router.js#L260-L265

So when an error happens as part of getIntialProps in _app.js we have to catch it again and render the error page.

[znarf]

Thank you @timneutkens. That was fast!

[timneutkens]

Thank you very much for the detailed description and reproduction. Makes it way faster to solve issues like this 🙌