Add warning unknown route

[staskjs]

Add warning about not existing route, because "Cannot read property 'path' of undefined" is really not informative.

[posva]

Thanks for this!
Can you please surround the warn with a check like

vue-router/src/create-route-map.js

Line 31 in 0e319d4

if (process.env.NODE_ENV !== 'production') {

and add a test?

[staskjs]

OFFTOPIC: Does owner receive notifications about adding commits to pull request?

In case of not, done.

[LinusBorg]

Does owner receive notifications about adding commits to pull request?

Nope, no notification. Commenting like you did is a good practice.

[posva]

I did receive a notification for your commit

[LinusBorg]

Oh... ^^

[posva]

Thanks @LinusBorg 😆