bugfix in rename.php

rename.php

@@ -18,6 +18,9 @@ if(preg_match(PATTERN, $name) != 1) {
     $error = 14101;
 } else if($uid == '') {
     $error = 14102;
+} else if($db->query('SELECT EXISTS (SELECT 1 FROM "Users" WHERE "ID" = $1)', array($uid))
+    ['data'][0]['exists'] == 'f') {
+    $error = 14104;
 } else {
     $db->query('UPDATE "Users" SET "name" = $1 WHERE "ID" = $2', array($name, $uid));
     if(preg_match('/violates unique constraint "Users_name_unique"/', pg_last_error()) == 1) {