Sometimes you may need to collect data from players. This could be their scores, game statistics, feedback, survey answers or anything else. There are many ways...
Try googling the error:
webapps.stackexchange.com/questions/162312/type-error-cannot-read-property-getid-of-null-in-google-script
Thanks, Should I insert the GoogleSheet's URL somewhere? Am I missing something?
I don't know, sorry. Last time I did this was several years ago.