[ null, 'ah' ].findAll() throws a NullPointerException

[ null, 'ah' ].findAll()

throws a NullPointerException with no error message which is a bit odd because I can write [][1] and get null back.

Essentially, Groovy is very lax (in a good way) in most parts but not here.

I'd implement a default Closure that just casts each argument to boolean, which i think [ null, 'ah' ].findAll

would.

This might apply to more methods than just findAll().