Allowing undefined as the NaN fallback in toInt and toFloat

[aleclarson]

This is a minor gripe. Currently, toInt and toFloat return 0 if you don't provide your own NaN fallback value. Therefore, it's impossible to set undefined as the fallback (it'll only be coerced to 0).

This is only an issue when you'd like an undefined result (likely a rare occurrence, but in the name of elegance, I continue). To get that, you have to do this hideous workaround:

toInt(value, null) ?? undefined

I propose changing the default NaN fallback to undefined. We may even prefer to remove the fallback argument entirely, since the primary benefit of toInt/toFloat is the coercion of NaN to a less troublesome value.

toInt(NaN) // => undefined
toInt(NaN) ?? 0