Isset check on array is loosing generic of the values #7511
Description
Bug report
It seems like when using array<T of Foo> and using isset() then accesing a value, the value is just considered as Foo.
Code snippet that reproduces the problem
Original issue:
https://phpstan.org/r/cfa53647-37aa-400e-8c4d-27ff902a807d
But this can be simplified to https://phpstan.org/r/0fc99af2-13fd-4c7f-bd43-06408b41e56f