fix: prevent account creation through Discord when registrations are disabled

Signed-off-by: Miguel Nogueira <me@nogueira.codes>

app/Http/Controllers/Auth/DiscordController.php

@@ -21,6 +21,7 @@
 
 namespace App\Http\Controllers\Auth;
 
+use App\Facades\Options;
 use App\Http\Controllers\Controller;
 use App\User;
 use GuzzleHttp\Exception\ClientException;
@@ -70,6 +71,14 @@ class DiscordController extends Controller
 
             Auth::login($appUser, true);
         } else {
+
+            if (!Options::getOption('enable_registrations'))
+            {
+                return redirect()
+                    ->route('home')
+                    ->with('error', __('Hey there, ' . $discordUser->getName() . '! Sign ups are currently closed so we were not able to create your account. Head over to the sign up page to request an invitation if you\'d like. Alternatively, if you already have an account here, make sure to log in with Discord with the correct account you linked beforehand.'));
+            }
+
             $oAuthUser = User::create([
                 'uuid' => null,
                 'name' => $discordUser->getName(),