Item in response does not validate

How to reproduce:

Make a simple POST to create a data sample but don't include the attribute "type":

        "data": {
            "attributes": {
                "userId": "1",
                "caseId": "1",
                "score": 1,
                "createdAt": "2016-04-04T13:43:52Z",
                "updatedAt": "2016-04-04T13:43:52Z"
            }
        }

The body of the request is not valid, but it will not be discarded and persisted anyway. As response I will get:

"errors": [
        {
            "status": "500",
            "code": "EINVALIDITEM",
            "title": "Item in response does not validate",
            "detail": {
                "item": {
                    "type": "userCourseHighscore",
                    "id": "791e942b-9487-4887-8f20-456e1477a5ab",
                    "userId": "1",
                    "courseId": null,
                    "score": "1",
                    "createdAt": "2016-04-04T13:43:52.000Z",
                    "updatedAt": "2016-04-04T13:43:52.000Z"
                },
                "error": "child \"type\" fails because [\"type\" must be one of [userCaseHighscore]]"
            }
        }
    ]

If I request all items of the relation with a GET, I will get the same error.

 "errors": [
        {
            "status": "500",
            "code": "EINVALIDITEM",
            "title": "Item in response does not validate",
            "detail": {
                "item": {
                    "type": "userCourseHighscore",
                    "id": "05173fba-0574-418e-9edf-b0e284c0490c",
                    "userId": "1",
                    "courseId": null,
                    "score": "1",
                    "createdAt": "2016-04-04T13:43:52.000Z",
                    "updatedAt": "2016-04-04T13:43:52.000Z"
                },
                "error": "child \"type\" fails because [\"type\" must be one of [userCaseHighscore]]"
            }
        }
    ]

Expected Behavior

If the payload doesn't validate, the item should be disgarded and not persisted.