Make some/any reject if race is unwinnable due to too few inputs

[briancavalier]

Docs and unit tests updated as well.

See #330

[scothis]

Should it throw instead of reject? The error is synchronous. Fail fast, fail loud.

[briancavalier]

@scothis, Yeah, it's a good question. @unscriptable and I talked about it briefly. One issue is that we wouldn't be able to throw synchronously in all cases since any and some happily accept a promise for an array. So, if you provided a promise for a zero-length array, you'd get a rejection, but if you provided a concrete zero-length array, you'd get a sync throw. Given that, I think the best option is just to make them fail in the same way in case someone actually does want to handle it.

Also, since unhandled rejection reporting is on by default now, you'll likely see the error almost instantaneously in the console unless you catch it. It's pretty fail-fast/loud now, even though it doesn't cause a true crash.

[scothis]

@briancavalier good point. Better to be consistent!

[unscriptable]

I went through the same mental exercise, @scothis. :) 👍 for consistency.

[briancavalier]

Rebased after a couple of small changes on master.