coverity: avoid dereferencing NULL #28984

Job	Run time
config	9s
fuzz smoke test	2m 3s
win+VS build	0s
win+Meson build	4m 11s
win build	5m 0s
static-analysis	6m 14s
sparse	3m 51s
rust-analysis	2m 8s
osx-gcc (macos-14)	30m 8s
osx-reftable (macos-14)	35m 27s
osx-meson (macos-14)	51m 12s
osx-clang (macos-14)	32m 52s
documentation	7m 52s
linux-TEST-vars (ubuntu:20.04)	24m 3s
linux-sha256 (ubuntu:rolling)	16m 45s
linux-breaking-changes (ubuntu:rolling)	25m 48s
fedora-breaking-changes-meson (fedora:latest)	19m 52s
linux-asan-ubsan (ubuntu:rolling)	1h 11m 29s
linux-leaks (ubuntu:rolling)	58m 45s
linux-meson (ubuntu:rolling)	24m 9s
linux-reftable-leaks (ubuntu:rolling)	1h 0m 45s
linux-reftable (ubuntu:rolling)	24m 48s
linux-musl-meson (alpine:latest)	18m 23s
linux32 (i386/ubuntu:20.04)	6h 0m 3s
debian-11 (debian:11)	21m 55s
almalinux-8 (almalinux:8)	15m 43s
win+VS test	0s
win+Meson test (3)	58m 26s
win+Meson test (4)	9m 26s
win+Meson test (2)	8m 37s
win+Meson test (5)	10m 46s
win+Meson test (7)	10m 59s
win+Meson test (0)	10m 30s
win+Meson test (6)	29m 23s
win+Meson test (1)	6m 3s
win+Meson test (8)	9m 19s
win+Meson test (9)	10m 34s
win test (3)	10m 32s
win test (9)	7m 45s
win test (0)	7m 33s
win test (5)	9m 33s
win test (2)	6m 52s
win test (7)	19m 49s
win test (1)	6m 0s
win test (6)	57m 22s
win test (4)	9m 26s
win test (8)	6m 51s
	20h 29m 21s

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