Error handling for unmounted component

When a component is unmounted, error observer is removed from the query (in graphql wrapper component function componentWillUnmount). Thus, if an “in flight” request arrives with an error, there is no way to catch it and avoid the console.error red box message “Unhandled error …”.

At least the error message should explain what’s really happening (unmounting could keep an error observer subscribed to adapt the error message to this case). The error message could also be removed or only be a console.warn. An option could be added to the graphql function to specify an error observer for errors after unmounting the wrapped component.

[GuillemotF]

I made a reproduction with the error template It reproduces a component throwing an unhandled network error when unmounting and not updating after an error (related to #2513)

[monotv]

An unhandled network error when unmounting a component that failed to fetch this in particular is killing Apollo for me. The docs suggest logging the user out on a 401 error. Logging out often means unmounting scenes. This results in an unhandled error. So the docs are contradicted by how the client behaves.