Applying type-modifying function conditionally drops type info

[simPod]

Bug report

I have a function

/**
 * @template Tk
 * @template Tv
 *
 * @param Generator<Tk, Tv, mixed, mixed> $generator
 *
 * @return iterable<Tk, Tv>
 */
function rewindable(Generator $generator): iterable;

I want to apply this function on a variable of type iterable when it's instance of Generator

$new = $old instanceof Generator ? rewindable($old) : $old;

$old is of type iterable<A,B> and I'd expect $new to be of the same type. However, the type info is lost and $new is of type iterable<mixed>.

Code snippet that reproduces the problem

https://phpstan.org/r/8e49d7cf-ee0f-4943-8c7c-d5e1cd8596b8

Expected output

L34: Dumped type: iterable<ToString>

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