Fix GCC v14 [-Wanalyzer-null-dereference] warnings in Kerberos (#1983) #314

Job	Run time
source-maintenance-tests	2m 55s
functionality-tests	18m 8s
CodeQL-tests	23m 31s
build-tests(ubuntu-22.04,gcc,default)	5m 16s
build-tests(ubuntu-22.04,gcc,minimal)	4m 11s
build-tests(ubuntu-22.04,gcc,maximus)	5m 55s
build-tests(ubuntu-22.04,clang,default)	6m 13s
build-tests(ubuntu-22.04,clang,minimal)	5m 0s
build-tests(ubuntu-22.04,clang,maximus)	7m 22s
	1h 18m 31s

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