Fix album art retrieved from Spotify
Fix album art retrieved from Spotify

Remove double quotes around image URL retrieved from Spotify
by slicing one character more from left and one character
more from right.
Also, remove redundant code and null errors to console when
element is not found.

Signed-off-by: Tomas Slusny <71c4488fd0941e24cd13e3ad13ef1eb0a5fe5168@gmail.com>

PeterMinin/chrome-media-keys,PeterMinin/chrome-media-keys,msfeldstein/chrome-media-keys