Request: When no appropriate token is present, `shell-fm -d` should exit with non-zero status, and send the token url to std_err.

[AndydeCleyre]

As it is, with no token or an expired token, launching shell-fm normally (not as a daemon) exits immediately with error status and an error message:

This token has not been authorized.
Failed to create session. Please refresh authorization.
Please open http://www.last.fm/api/auth/?token=[ . . . ] in your browser to authorize shell-fm.

In contrast, launching shell-fm with the -d flag under the same circumstances appears from the outside to be a silent success, but in reality exits immediately as well, only with no error status, no error message, and no url.

I request that running shell-fm -d without an appropriate token result in a non-zero exit status, and the token url output to std_err.