Things I have learned about the last.fm API that were relevant to troubleshooting:
Sometimes the album art comes as a png and sometimes it is a jpeg and the php gd library does not have a catch-all image creation function for me to pass a url to, I have to substring out the extension and make a decision.
If you are listening to a song right the fuck now the date field is not present in the API response at all, which if I want to display it on the image I had to put in an explicit check for that.
I have also remembered why I did not grow up to be a web developer and it's because PHP sucks lmao