Fix GetTextString() and GetByteString() error handling #616

Job	Run time
• gcc • ubuntu:22.04	24s
-DQCBOR_DISABLE_NON_INTEGER_LABELS • gcc • ubuntu:22.04	22s
-DQCBOR_DISABLE_TAGS • gcc • ubuntu:22.04	24s
-DUSEFULBUF_DISABLE_ALL_FLOAT • gcc • ubuntu:22.04	25s
-DQCBOR_DISABLE_FLOAT_HW_USE • gcc • ubuntu:22.04	21s
-DQCBOR_DISABLE_PREFERRED_FLOAT • gcc • ubuntu:22.04	26s
-DQCBOR_CONFIG_DISABLE_EXP_AND_MANTISSA • gcc • ubuntu:22.04	22s
-DQCBOR_DISABLE_ENCODE_USAGE_GUARDS • gcc • ubuntu:22.04	22s
-DQCBOR_DISABLE_INDEFINITE_LENGTH_STRINGS • gcc • ubuntu:22.04	24s
-DQCBOR_DISABLE_INDEFINITE_LENGTH_ARRAYS • gcc • ubuntu:22.04	23s
-DQCBOR_DISABLE_DECODE_CONFORMANCE • gcc • ubuntu:22.04	23s
• clang • ubuntu:22.04	40s
-DQCBOR_DISABLE_NON_INTEGER_LABELS • clang • ubuntu:22.04	34s
-DQCBOR_DISABLE_TAGS • clang • ubuntu:22.04	33s
-DUSEFULBUF_DISABLE_ALL_FLOAT • clang • ubuntu:22.04	31s
-DQCBOR_DISABLE_FLOAT_HW_USE • clang • ubuntu:22.04	30s
-DQCBOR_DISABLE_PREFERRED_FLOAT • clang • ubuntu:22.04	32s
-DQCBOR_CONFIG_DISABLE_EXP_AND_MANTISSA • clang • ubuntu:22.04	40s
-DQCBOR_DISABLE_ENCODE_USAGE_GUARDS • clang • ubuntu:22.04	38s
-DQCBOR_DISABLE_INDEFINITE_LENGTH_STRINGS • clang • ubuntu:22.04	44s
-DQCBOR_DISABLE_INDEFINITE_LENGTH_ARRAYS • clang • ubuntu:22.04	31s
-DQCBOR_DISABLE_DECODE_CONFORMANCE • clang • ubuntu:22.04	40s
	10m 49s

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