Error handling UX

[axelchalon]

Right now some errors make Fether display an empty screen. It would be nice to show a message to the user and for example guide them to report the issue.

[axelchalon]

related to https://github.com/paritytech/fether/issues/347

[axelchalon]

Idea:

Error happens; user is shown this screen, or some variant thereof:

---

An error occured

invalid RPC call

at ... at ... (stack trace)

Please report this bug by reaching us on GitHub, Twitter, by mail at [email protected], or by using the form below.

--

The bug report will consist solely of the following information:

Error log:

(stack trace)
(fether log, maybe)

Additional comment (what were you doing when the error occured?) :

free text field

[SUBMIT]

---

Some solutions should exist to set up the form endpoint easily.