undefined error issue

[rahulreddy]

Making sure this issue gets logged so that we don't forget about this. While fixing Vault with pr https://github.com/scality/IronMan-Vault/pull/228
we noticed that if we mess up the case(uppercase/lowercase) of the arsenal error property, we just return undefined back to the calling function. Now we don't know if we got undefined because there was no error or if the Arsenal error property does not exist.

I guess the only way to properly solve this is to use the following ES6 technique, following this Stack Overflow post:
http://stackoverflow.com/questions/20147081/javascript-catch-access-to-property-of-object
and
http://wiki.ecmascript.org/doku.php?id=harmony%3adirect_proxies

Edit: The sad thing is that it's not supported by Node.JS at the moment. We might want to take a look into Babel's way of translating this feature; so that we can do it on our own in Arsenal, without relying on babel.
Edit: Even sadder... support cannot be brought through observing Babel:

Unsupported feature
Due to the limitations of ES5, Proxies cannot be transpiled or polyfilled. See support in various JavaScript engines.

I wanna cry :'(

[rahulreddy]

😞 that hurts.
We wouldn't want to mess with Object's prototype chain either.

I'm completely not against such kind of metaprogramming, and that's the only way I see that would have allowed to keep the current API, while ensuring that using an undefined error name would have used either a "default error" or failed early.

That might be my dark metaprogrammer side talking here, but I love simple APIs that are powerful :D

This is where static analysis is supposed to shine. I'll try to look into that in my free time.

Indeed, it's yet another track to follow, but still, this means setting up a tool in all projects to ensure that this one is used properly. I'd rather have it self contained with black magic ^^'