The theme doesn’t load css and JS files doesn’t load in functions.php

You use get_header() in the after_setup_theme.

The get_header() function should be used only in theme template files, not directly in the after_setup_theme hook.

Does the theme work now?

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)