Show error message on fetch error

[oliverbarnes]

Fetch Error: Unable to Fetch resource(s)

Becomes

Fetch Error: Unable to Fetch resource(s): Pretender intercepted GET /supports but no handler was defined for this type of request

(or would this be better in a console warning?)

[pixelhandler]

@oliverbarnes It does seem reasonable - since the first argument to construct a FetchError instance is message. I should also add some error handling examples in the dummy app too.

I included the original error, as the error property of the FetchError so in some cases I do access the original error. I recall leaving the FetchError message short and static (more like a title). Perhaps looking over a working use case would help find some clarity on error handling with the FetchError.

[oliverbarnes]

My case was trying to test a feature that was already working, a functional test driving the interface, and struggling to stub the api requests and model the payload mocks accordingly with Pretender.

Running the test on the browser, with ember test --server the generic Fetch Error: Unable to Fetch resource(s) error would come up again and again, and since there were 4 different requests being done from the route, it was hard to tell which request it was referring to.

i'd append .then((response) => { debugger }, .then(error) => { debugger } to get at the error on each of them, and then get at the actual error message pointing to which request or stub the error was coming from. But, once I had fixed each of the pretender stubs, the generic error would still show up, though the debugger in the error block was never hit.

I had to find where the error was caught in EJR and debug there to get at the error message, and finally I saw it was a request being made from a component :)

Debugging at that level I saw all this could be avoided by simply showing the specific error message on the browser (or on the command line, for that matter).