Return an error for empty response body

[eatyourgreens]

Check for response.body before checking for response.body.error or response.body.errors.
Don't sniff the response for <DOCTYPE.
Report 'unknown error' with status and status text if the response body is empty.

Fixes a bug where the client crashes on 500 errors, because response.body is null.

Closes #99.

[eatyourgreens]

npm install github:zooniverse/panoptes-javascript-client#response-body to test an app with this branch of the client.

[eatyourgreens]

Trying this out with zooniverse/pandora, I now get shown the 500 error, when I save a tutorial, rather than unable to read property errors of null from the client.

[shaunanoordin]

Code change looks good, though I have questions:

1. I assume there's no scenario when handleError: function(response) would ever return response === undefined?

2. Wait, how did that original error crop up? Looking at the original code...

if (response.body && response.body.error) {

...shouldn't this clause not have triggered if response.body is null?

[shaunanoordin]

Wait, never mind what I said about Question 2 - I just read Issue #99 and see that the response.body was moved higher up in the checks to prevent a later else if check from dying. Sorry, didn't see that in the code.

[eatyourgreens]

The translations API is broken at the moment, so saving a translation returns 500: Internal Server Error with no response body. In the current version of the client, the error handler crashes with unable to read property errors of null and that error gets caught by the parent app.

[shaunanoordin]

PR Review

This PR prevents errors from occurring in the error-catching mechanism of the API client. The client now properly reports when, e.g. a 500 error is received from the Panoptes server.

While I'm unable to test this properly on my apps (I can't get things to crash when I want to ) the code changes looks legit.

Also, please note the difference between response.body.error and response.body.errors; the later else if (Array.isArray(response.body.errors)) line threw me for a loop during my review.

Status

👍 LGTM

[eatyourgreens]

The nested if statements in that error handler still bug me, to be honest.