I was able to find the error log in my invoice ninja environment. Here is the error I keep getting:
[2020-10-27 11:34:32] production.ERROR: ***ErrorException*** [0] : /var/www/html/bluemoontest/app/Ninja/Repositories/DocumentRepository.php [Line 62] => Undefined index: file {"context":"PHP","user_id":3,"account_id":1,"user_name":"Cameron Williams","method":"POST","user_agent":"vscode-restclient","locale":"en","ip":"96.233.106.45","count":1,"is_console":"no","is_api":"yes","db_server":"mysql","url":"api/v1/documents"} []