FAPI: fix problems detected by scanner. #2225

Job	Run time
scanbuild	6m 34s
test-mbedtls (ubuntu-20.04)	2m 48s
test-coverage	4m 48s
test-mbedtls (ubuntu-22.04-mbedtls-3.1)	2m 51s
test-no-crypto-build	1m 15s
test-tcti-config	14m 2s
coverity-test	0s
build-test (ubuntu-20.04, gcc)	4m 37s
build-test (ubuntu-20.04, clang)	4m 14s
test-fuzz	2m 35s
build-test (fedora-32, gcc)	4m 39s
build-test (fedora-32, clang)	4m 53s
build-test (opensuse-leap, gcc)	4m 29s
build-test (opensuse-leap, clang)	4m 32s
build-test (ubuntu-22.04, gcc)	4m 30s
build-test (ubuntu-22.04, clang)	4m 46s
build-test (alpine-3.15, gcc)	3m 58s
build-test (alpine-3.15, clang)	4m 36s
	1h 20m 7s

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