Handle HTTP 500 status code properly in forms

[aapeliv]

No description provided.

[shuttle1987]

Is this upstream issue related to this: persephone-tools/persephone-web-API#64 ?

[aapeliv]

Frontend should probably treat all errors in some meaningful way.

But standardising the error responses and not returning 500s upstream would be good (as spec says it doesn't return 500s).

[shuttle1987]

If there's a 500 it's very likely a bug in the API, please open an issue if you encounter any such 500 errors.

[shuttle1987]

I added an API for errors in persephone-tools/persephone-web-API#138, as is the case with 500 errors there's nowhere where I'm expecting to see them so it hasn't been specified just yet. Looks like an issue to open with the web API to specify the 500 error format in the API specification either as a 500 or in the default section