Show error when connection fails.

[lukasoppermann]

Hey,

I tried to connect to a server using the wrong IP (my server moved and the ip changed, and I forgot). However, I did not get an error. Instead it show the file screen without any directories. In the bottom it showed Connected to 111.122.233.28, which it definitely did not.

I think it would be better if the app would stay on the/go back to the connection screen and show an error.