[Bug] Invalid memory reference in test

[youyuanwu]

See https://github.com/Azure/service-fabric-rs/actions/runs/17067375688/job/48387649025?pr=181

test result: ok. 6 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 13.33s


error:
 test failed, to rerun pass `-p samples_echomain_stateful2 --bin samples_echomain_stateful2`

Caused by:
  process didn't exit successfully: `/workspaces/repo/target/debug/deps/samples_echomain_stateful2-61535bb61659e3b5 --nocapture` (signal: 11, SIGSEGV: invalid memory reference)

Most likely some cleanup code in rust or in SF itself has error

[youyuanwu]

It is very rare to repro in gdb:

[Thread 0x79d7cbacd640 (LWP 21854) exited]

Thread 32 "test2::test_res" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x79d74ffff640 (LWP 21886)]
0x000079d7ae388ba2 in ?? () from /opt/microsoft/servicefabric/bin/Fabric/Fabric.Code/libFabricClient.so

[youyuanwu]

The crash stack is in FabricClient, and most likely in the cleanup path where some background timer thread still has a reference to dangling objects.
Created a task internally to investigate further.