Vanilla: Call onError without argument if there is no response

[minad]

See haskell-servant/servant#607

[minad]

ping @soenkehahn

[phadej]

• it would be good to check that Content-Type isapplication/json
• Also it would be great to JSON.parse inside try / catch block

[minad]

Ok, I am pretty sure this can be improved. My reasoning is that if JSON is served, it should be valid - this PR only treats the case of no response.

But I am still not sure about what is desired here:

1. Should onError called without an argument or with some kind of error object? If we want an error object, which format, e.g. { status: ..., msg: ... }?
2. Should onError be called if JSON parsing fails or should there be an exception?

[phadej]

My concerns are that in not 2xx case the response might be (and in case of say 500 exception, isn't) a valid JSON. So maybe I'd just onError(new Error(xhr))

[minad]

I updated the patch

[phadej]

onSuccess, it should be onError?

[minad]

ouch yes

[phadej]

LGTM, I'll try it and merge then. Thanks.