Fix topic lookup segmentation fault after client is closed #986

Job	Run time
Formatting Check	1m 37s
Lint	26m 16s
Build the Wireshark dissector (ubuntu-latest)	57s
Run unit tests	21m 50s
Build CPP Client on Windows x64	32m 1s
Build CPP Client on Windows x86	31m 28s
Build with the C++20 standard	5m 26s
Build RPM x86_64	12m 6s
Build Alpine x86_64	15m 58s
Build Deb x86_64	9m 25s
Build CPP Client on macOS with static dependencies	8m 49s
Check Completion	2s
	2h 45m 55s

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