Improve accuracy of Collection::isEmpty and isNotEmpty assertions

[spawnia]

Those methods do not necessarily prove that the result of first() is not null. However, they can prove that the result of first() is of the type contained within the Collection.

[johanrosenson]

This solution i stand behind 100%.

Have you verified that this method is actually working? I think I tried this solution originally but I didn't get the results I expected, but maybe I was too far down the rabbit hole at that point and maybe I missed something.

Another thought I had was that @phpstan-assert-if-true should not really be null either, because it's actually returning the value of $default, can you see if you get it working with @phpstan-assert-if-true TFirstDefault $this->first() ?

I think I tried that also, but again, didn't get the desired result, but I might have missed something in my testing.

[spawnia]

Have you verified that this method is actually working?

I think the additions i made to types/Support/Collection.php prove it.

Another thought I had was that @phpstan-assert-if-true should not really be null either, because it's actually returning the value of $default, can you see if you get it working with @phpstan-assert-if-true TFirstDefault $this->first() ?

The assertions only affect calls that are exactly first(). When parameters are passed, the assertion has no effect. See 858be4b for additional tests that prove this.

[johanrosenson]

Thank you @spawnia for improving it!