Add a test which does not send a type.

Therefore the default is text/plain, which will cause an Exception
Given an UnsupportedFormat, raise a BadRequest

If we don't know how to handle the data, say so.
Test something which claims to be correct data type, but isn't.

This should not cause the server to crash, but currently does.
Ensure that the deserialized data is a dictionary.

Once we have deserialized data, we assume it is a dictionary.

Perform the dictionary.items() test early and
raise a red flag if an exception occurs.