It’s probably the code problem, not server-side. Such a questions can be asked on stackoverflow or whenever else, also I’m sure you’re not first facing this error and maybe there’s an asnwer in google.
I see the page responds with a status code of 500 (you can check this from the Network tab of your browser’s developer console). A status code 500 means the code is crashing: https://infinityfree.net/support/http-error-500/