Fix findbyid with null parameter

Author: tacxou

src/Mvc/Collection.php

@@ -869,7 +869,7 @@ public static function findFirst(array $parameters = []): ?CollectionInterface
     public static function findById($id): ?CollectionInterface
     {
         if (!is_object($id)) {
-            if (!preg_match("/^[a-f\d]{24}$/i", $id)) {
+            if (!preg_match("/^[a-f\d]{24}$/i", (string)$id)) {
                 return null;
             }
 

tests/integration/Collection/FindByIdCest.php

@@ -71,6 +71,7 @@ public function mvcCollectionFindById(IntegrationTester $I)
     {
         $I->wantToTest('Mvc\Collection - findById()');
 
+        $I->assertNull(Robots::findById(null));
         $I->assertNull(Robots::findById(new ObjectId()));
         $I->assertInstanceOf(Robots::class, Robots::findById($this->tmpId));
         $I->assertInstanceOf(Robots::class, Robots::findById((string)$this->tmpId));