[Libguestfs] [PATCH libnbd v2 0/4] Additional non-NULL warnings, checks and docs

v1 was: https://listman.redhat.com/archives/libguestfs/2022-September/029982.html This series is actually quite a bit different from v1 because it is rebased on top of Eric's series and takes that into account. Generally this heads down the return error instead of asserting route, hoping that the GCC annotations will be sufficient to catch as many errors as possible at compile time. Rich.