rescue_from :all not rescuing all exceptions

[Jelkster]

According to the README, grape can rescue from all exceptions with the following:

rescue_from :all

I recently stumbled across a case where the wrong method accidentally raised a NotImplementedError and caused the web request to hang as a result. I was surprised to see this because I had the rescue_from :all included in the API. I suspected that maybe NotImplementedError was not a StandardError and maybe that somehow had something to do with it. Sure enough, I found that it was a ScriptError.

I consulted the documentation again to see if I missed something, and actually saw an example of rescue_from NotImplementedError in the README. So it appeared as though it was perfectly valid at some point in time. That being said, I also saw the following message below an example: "In this case UserDefinedError must be inherited from StandardError".

After taking a look at error.rb it appears as though only StandardError will get rescued. I modified the source and replaced StandardError with Exception to see if that would resolve the issue and it did!

The last thing I did was inspect the history of the error.rb file to see if it was ever rescuing Exception before, and sure enough it was. It appears Rubocop recommended the change.

[dblock]

I think we definitely need to update the documentation first, make sure the specs cover all the scenarios, and possibly add a rescue_from :exception that will behave differently? Please contribute?

[Jelkster]

I'm willing to try and help. Regarding the documentation, would you like me to remove the NotImplementedError example only, or do we also need to address each mention of "...all exceptions..."?

[dblock]

Whatever you think is appropriate, try something and we can look at it.

[dblock]

Doc updated in #1725. What do we want to do about this issue?

[Jelkster]

I think your rescue_from :exception proposal is good. Want me to take a stab at that?

[dblock]

Yes please @Jelkster

[mtsmfm]

Is it really documentation problem?
I think rescue_from :all should rescue all exceptions as before f038ed5#diff-38c8cda4fd3b2789c88488c6e1e08d0eL28
because it looks unintentional change.

What do you think about replacing this line with rescue Exception => e like Rails?

[Jelkster]

That would make my life easier, as I'm currently in the process of implementing a separate rescue_from :exception option that does what you'd expect :all to do.

[dblock]

I am willing to look at any PR, but this is a pretty major change and it will affect lots of people, so there be dragons.

[mtsmfm]

@Jelkster Can I send a PR which rescue truly all exceptions? Are you implementing now?

[Jelkster]

@mtsmfm go ahead and send it.