Not writable /user/config causes Error 500

[TuomLarsen]

I've just tried to install latest Grav on XAMPP and it failed with 500 Error. It was caused by /user/config not being writable (it could not create some .yaml file there).

Fixing this, I was redirected to a very helpful page which listed all the permission problems I additionally had.

Maybe it would be worth displaying similarly helpful notice for the original problem, not just merely exiting with 500.

PS: Let me take this as an opportunity to thank you for writing Grav!