Improve error reporting when requests fail — retire "Expecting value: line 1 column 1 (char 0)", report HTTP code instead

[talflon]

There's a number of places in the code where .json() is called on a Requests response, without first checking if it failed. If it fails, it's not going to parse as JSON. Instead, we usually get:

requests.exceptions.JSONDecodeError: Expecting value: line 1 column 1 (char 0)

I think it'd be nicer to instead raise the HTTP error code received, instead of the lack of a JSON object at char 0.

Does anyone have any objections to this change? Will there be nostalgia for line 1 column 1 (char 0)?

[talflon]

Looks like it's just a question of calling .raise_for_status() before most, if not all, of the .json() calls. The question would be if there are any requests which return JSON with a 4xx or 5xx error which we also need to parse.