flarumr these docs are not exactly up to date ?
Debug mode is really just the first part, which is accurate:
Before you proceed, you should enable Flarum’s debugging tools. Simply open up config.php with a text editor, change the debug value to true, and save the file. This will cause Flarum to display detailed error messages, giving you an insight into what’s going wrong.
Changing the display_errors PHP setting is probably not needed. But if you really want to enable it you can edit your php.ini (as stated in the link) or add the provided PHP to index.php, above or below the require call. Don't forget to remove it once you're done testing.
