The problem can't possibly be with can_delete. An int is an int. No bit pattern is invalid.

If there's a problem on that line, it must be *can_delete_sv, or in magic attached to it.

That's as much as I'm tempted to work on this without a minimal runnable demo. I would expect the 4th param of hv_fetch to be true, by the way, and that probably removes the need to call hv_store.