Code review comment for ~ballot/charm-graylog/+git/charm-graylog:lp1896484

Agreed that it would potentially be preferable to use .json(), but the change is clear and readable as is. Looking at how this function is used, the patch as is will return None where there's no response, which is accounted for in the usage.

The structure of the function itself returning bool or a dict is something to review, but outside the scope of this change.