Don't leak internal AssertionErrors to user code
Don't leak internal AssertionErrors to user code

Asynchronous `t.throws()` / `t.notThrows()` was the only case where
internal AssertionErrors were leaked to user code. Return `undefined`
instead.

Collinslenjo/ava,andywer/ava-ts,sindresorhus/ava,avajs/ava,andywer/ava-ts,Collinslenjo/ava,avajs/ava