For anyone having issues with spotty throwing errors in the logs similar to:

[17-07-21 20:18:22.0891] Plugins::Spotty::API::getToken (115) Failed to get Spotify access token: 'true' expected, at character offset 0 (before "thread 'main' panick...") at /var/lib/squeezeboxserver/cache/InstalledPlugins/Plugins/Spotty/ line 112.
thread 'main' panicked at 'called `Option::unwrap()` on a `None` value', /checkout/src/libcore/
note: Run with `RUST_BACKTRACE=1` for a backtrace.
Aborted (core dumped)
I resolved the issue by changing my Spotify password to eliminate special characters. I've file an issue with librespot.