[lazerg]

When a closed generator is passed to parent::__construct() of a dual iterator, the constructor throws after the object is already marked as constructed, so inner.iterator stays NULL. If the subclass catches the exception, spl_dual_it_next() only checked for a NULL inner iterator when do_free was 0, so next() on FilterIterator, IteratorIterator, LimitIterator and friends dereferenced it. NoRewindIterator had the same problem in valid(), key(), current() and next().

The NULL check in spl_dual_it_next() now runs in both cases, and the NoRewindIterator methods behave like the other iterators here: valid() returns false, key() and current() return NULL, and next() throws the existing "inner constructor wasn't initialized" error.

Fixes #25415

[lazerg]

The LINUX_X32_DEBUG_ZTS Tracing JIT failure also happens on PHP-8.4 itself (runs 43196288502 and 43186660061), so it isn't caused by this change.