Bug report

When using unset on a non-empty-array and then checking for the number of element, there is no issue.
But if I call unset on an array of non-empty-array, and then checking for the number of the element, they are still considered as non-empty but they are possibly empty.

Code snippet that reproduces the problem

(https://phpstan.org/r/c9e905eb-a330-4504-9a6e-660b364e79ac)

Expected output

No error

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