feat: install phpstan and resolving reported errors in PHPStan

routes/routes.php

@@ -12,4 +12,9 @@
 */
 
 
-Route::post('oauth/token', '\Laravel\Passport\Http\Controllers\AccessTokenController@issueToken')->middleware('throttle');
+use Illuminate\Support\Facades\Route;
+
+Route::post(
+    'oauth/token',
+    '\Laravel\Passport\Http\Controllers\AccessTokenController@issueToken')
+    ->middleware('throttle');