adding option to allow grape to handle Grape::Exception when rescue all is set

[mmclead]

This will allow Grape to use the built in Grape Exceptions defined in /lib/grape/exceptions when rescue :all is set.

[dblock]

Put this back please.

[dblock]

Would you please explain a bit more in detail what this achieves? I understand what it does, but I cannot think of a scenario where this is really useful.

[mmclead]

I added this so that I could easily respond with JSON errors and not HTML that leaked too much data and still have Grape handle 404's, 406's, and all the other exceptions that are handled out of the box.

So, if you were to add rescue_from :all, rescue_grape_errors: true to your API, you could cover all exception handling in one go, and then add specific error! calls as needed throughout the code.

Does that make sense? I can try to explain better if needed.

[dblock]

There's still something odd about this feature. It skips a specific exception, handles the rest, so that seems very "special" to begin with.

I want to talk it over more, I am sure we can come up with something better.

Can't the same thing be accomplished with rescue_from Grape::Exceptions::Base, minus the special handling of Grape::Exceptions::InvalidVersionHeader? If that's the case maybe we could alias that long exception name with rescue_from :grape_exceptions?

[mmclead]

The exception Grape::Exceptions::InvalidVersionHeader is skipped for the same reason that it is skipped in rescuable?(klass) which is explained in the README:

Unrescuable Exceptions

Grape::Exceptions::InvalidVersionHeader, which is raised when the version in the request header doesn't match the currently evaluated version for the endpoint, will never be rescued from a rescue_from block (even a rescue_from :all) This is because Grape relies on Rack to catch that error and try the next versioned-route for cases where there exist identical Grape endpoints with different versions.

I just copied the same logic. I wanted to put this repeated logic into one place but couldn't think of a clean way to do it.

I don't think it'll work the same if we do rescue_from Grape::Exceptions::Base because an ActiveRecord::RecordInvalid wouldn't be caught. The purpose of this PR is to allow users to be lazy about their error catching if they don't have specific use cases for certain errors. As soon as the user has need of specific error handling then error! is available.
Until then, this PR gives a 1 line way to catch all errors and use the previously built in error handling that Grape currently bypasses when rescue :all is set.

EDIT: I totally agree that the name could be better though. Any suggestions?

[dblock]

Ok, but don't you think a DSL like rescue_from :grape_exceptions would be more user-friendly? Same implementation roughly.

[mmclead]

yeah. I like that name better. it doesn't explicitly say that its also rescuing :all but a decently descriptive README might make up for it.

I'll make that change and we can take a look at it.

@dblock change completed. let me know what you think.

[mmclead]

@dblock change completed. let me know what you think.

[dblock]

Make this look like every other line please, the period goes to the end and there's a dash before your name ;)

[dblock]

Made some comments, it's mostly ready. Try to shorten the README, get to the point :)

[mmclead]

@dblock updated again. Sorry my grammar is terrible. And, I answered comment on test. Your call on whether you want the full match or continue with the way other examples are.

[dblock]

Merged, thank you.