sync.c: add sanity check so we don't dereference a null pointer

Originally noticed in FS#9024, but was fixed in previous changes anyway.
However, it doesn't hurt to still check it.

Also add a pactest from Chantry Xavier for the original problem to ensure
we can't reproduce it.

Signed-off-by: Dan McGee <dan@archlinux.org>

0 files changed, 0 insertions, 0 deletions