PATCH request without update data

[8-3]

Currently the lib allows to send a PATCH request without any attributes or relationships specified to update. Eg. {"data":{"id":"123","type":"user"}}.

A check for the content of changedItemState may be sufficient to prevent such requests.

vuex-json-api/src/module/actions/saveAction.js

Line 46 in faa7ad3

let changedItemState = diff(initialItemState, currentItemState)