fix find null failed job

Author: denissonleal

src/Jenssegers/Mongodb/Queue/Failed/MongoFailedJobProvider.php

@@ -46,6 +46,10 @@ public function find($id)
     {
         $job = $this->getTable()->find($id);
 
+        if (!$job) {
+            return null;
+        }
+
         $job['id'] = (string) $job['_id'];
 
         return (object) $job;

tests/QueueTest.php

@@ -55,4 +55,12 @@ public function testQueueJobExpired(): void
         $job->delete();
         $this->assertEquals(0, Queue::getDatabase()->table(Config::get('queue.connections.database.table'))->count());
     }
+
+    public function testFindFailJobNull(): void
+    {
+        Config::set('queue.failed.database', 'mongodb');
+        $provider = app('queue.failer');
+
+        $this->assertNull($provider->find(1));
+    }
 }