fix member names on error serializing

Author: tuyakhov

src/Serializer.php

@@ -295,8 +295,9 @@ protected function serializeModelErrors($model)
         $this->response->setStatusCode(422, 'Data Validation Failed.');
         $result = [];
         foreach ($model->getFirstErrors() as $name => $message) {
+            $memberName = call_user_func($this->prepareMemberName, $name);
             $result[] = [
-                'source' => ['pointer' => "/data/attributes/{$name}"],
+                'source' => ['pointer' => "/data/attributes/{$memberName}"],
                 'detail' => $message,
             ];
         }

tests/SerializerTest.php

@@ -35,6 +35,7 @@ public function testSerializeModelErrors()
         $model->addError('field1', 'Test error');
         $model->addError('field2', 'Multiple error 1');
         $model->addError('field2', 'Multiple error 2');
+        $model->addError('first_name', 'Member name check');
         $this->assertEquals([
             [
                 'source' => ['pointer' => "/data/attributes/field1"],
@@ -43,6 +44,10 @@ public function testSerializeModelErrors()
             [
                 'source' => ['pointer' => "/data/attributes/field2"],
                 'detail' => 'Multiple error 1',
+            ],
+            [
+                'source' => ['pointer' => "/data/attributes/first-name"],
+                'detail' => 'Member name check',
             ]
         ], $serializer->serialize($model));
     }