Invalid API key produces WSOD

Problem/Motivation

Steps to reproduce:
- Set up a google api key which is incorrect (any random string would do, but for a more common scenario, try a google browser key that was not activated for the Google Vision api).
- Set up a content type / fields as indicated on the module's instructions
- Create a content with a sample image, click "Save"
- WSOD

Proposed resolution

Use a Try/Catch to handle the exception raised by the http client if the response to the POST is not successful