Generic<mixed> overridden by specific type in catch #15198

Bug report

If in a try block I set a variable to an instance of a generic class where the generic type is mixed, and in the corresponding catch block I set that variable to an instance of the same generic class but with a specific generic type (e.g. int,) then afterwards PHPStan incorrectly sees that variable as always having the more specific generic type.

try {
    /** @var mixed */
    $bar = 'bar';
    $foo = new Foo($bar);
} catch (\Exception $e) {
    $foo = new Foo(123);
}

PHPStan\dumpType($foo); // returns Foo<int>

Code snippet that reproduces the problem

https://phpstan.org/r/2d6bc77c-c571-4e65-b4eb-53b69b8f59d9

Expected output

No issue should be detected.

PHPStan should see the type of $foo as Foo<mixed>|Foo<int> (or possibly Foo<mixed>.)

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