plugin_dir_url & plugin_basename not working when plugin dir is outside wordpress dir

Turns out I was adding a trailing slash to WP_PLUGIN_DIR in my wp-config.php which was causing this issue. Hopefully this will help someone making the same mistake.

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