Fix topic lookup segmentation fault after client is closed #988

Job	Run time
Formatting Check	1m 35s
Lint	27m 16s
Run unit tests	22m 28s
Build the Wireshark dissector (ubuntu-latest)	59s
Build CPP Client on Windows x64	15m 51s
Build CPP Client on Windows x86	15m 15s
Build with the C++20 standard	5m 31s
Build RPM x86_64	8m 19s
Build Alpine x86_64	15m 42s
Build Deb x86_64	9m 59s
Build CPP Client on macOS with static dependencies	7m 1s
Check Completion	2s
	2h 9m 58s

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