Remove unused code

- Remove commented code
- Remove unused/immediately overwritten variables
- Remove extraneous parameters
- Remove unreachable code
- Remove duplicate array keys

src/Model/User.php

@@ -438,7 +438,6 @@ class User
 		$return = ['user' => null, 'password' => ''];
 
 		$using_invites = Config::get('system', 'invitation_only');
-		$num_invites   = Config::get('system', 'number_invites');
 
 		$invite_id  = !empty($data['invite_id'])  ? Strings::escapeTags(trim($data['invite_id']))  : '';
 		$username   = !empty($data['username'])   ? Strings::escapeTags(trim($data['username']))   : '';
@@ -501,8 +500,6 @@ class User
 			$openid_url = '';
 		}
 
-		$err = '';
-
 		// collapse multiple spaces in name
 		$username = preg_replace('/ +/', ' ', $username);
 
@@ -826,8 +823,6 @@ class User
 			return false;
 		}
 
-		$a = \get_app();
-
 		Logger::log('Removing user: ' . $uid);
 
 		$user = DBA::selectFirst('user', [], ['uid' => $uid]);