Even though the code works perfectly fine, PHPStan doesn't understand it.
Since we want to work with `revindex` and `revindex0`, we can better check for their
existence, instead of `length`.
Same as #4249
Even though PHP does not complain, PHPStan does.
> Cannot unset offset '_iterated' on array{ ... the context values ... }
Since this is compiled code, we can easily produce a bit more valid code in the eyes of PHPStan.
This PR was merged into the 3.x branch.
Discussion
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Fix some errors reported by phpstan
Commits
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2b2ac80d Fxi some errors reported by phpstan
Fabien Potencier
Nicolas Grekas
Ruud Kamphuis
Alexander M. Turek