General issue - cpp/uninitialized-local should provide at least 1 path that leaves variable uninitialized (preferably all if possible)

**Description of the issue**

It is very difficult to see how this could be uninitialized and the report looks like a false positive:

https://github.com/ryao/zfs/security/code-scanning/709

I am not yet decided on whether this is a false positive or not, but I am certain that it would be very helpful if CodeQL could provide a path that leaves the variable uninitialized. I have seen it provide possible paths in #11215, but that is for a different query.