check the user type if it has valid value

src/Cli/AddUserCommand.php

@@ -27,7 +27,7 @@ class AddUserCommand extends Command
         $user->setActive(true);
         $user->setCreatedDate(new DateTime());
 
-        if ($input->hasArgument('type')) {
+        if ($input->hasArgument('type') && $input->getArgument('type') !== null) {
             $user->setType($input->getArgument('type'));
         }