Can't throw in generator functions? You can, but they don't throw until iteration starts.

wat.php

<?php

function gen($x)
{
    if (!is_int($x)) {
        throw new \InvalidArgumentException;
    }

    foreach (range(0, $x) as $i) {
        yield $i;
    }
}

gen('nope'); // no exception
foreach (gen('still nope') as $i) {
    // this loop will throw
}
}
}