eachOfLimit with limit < 1 should error

[megawac]

Currently instantly resolves. I think this should be a case we throw an error in.

[aearly]

I agree, a limit of 0 or less would certainly be a programmer error.

It's weird that we have a test for the old behavior. I'm not sure how limit 0 would be useful to anyone.

[vkstack]

Definitely throw an error.

[mikael-entefy]

Please also throw on undefined.
That would have made finding my async.eachLimit(list, config.propWithType, fn) bug way easier.