Narrowing tagged unions based on count is broken without array shape sealness implemented first #11494

Bug report

phpstan/phpstan-src#3302 has implemented narrowing based on the count of items in an array. But this relies on treating the shaped as sealed while analyzing valid method arguments treats all values as unsealed. This makes the static analysis mismatch with the runtime behavior of the code, making issues go undetected.

Code snippet that reproduces the problem

https://phpstan.org/r/6152adda-09b3-4920-8152-06be18efcd18

Expected output

There is 2 valid output for that:

1. Reporting an error about accessing short and reporting an error about passing the extra key when calling the function. This is the behavior when treating the shape as sealed
2. Reporting an error when accessing details as it might not always be defined in the union (behavior for unsealed shapes)

See https://3v4l.org/v7boM for the execution of that code snippet, showing that it fails on line 12, where phpstan currently does not report any issue (in scenario 2, an error would be reported on line 12, while scenario 1 would report it on line 16, which is the previous frame in the stack trace of the warning).

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