Unit Tests fail on release build

When running unit tests on current devel, built as release with clang on rocky8 they fail.

In the CI test job shown here only 43 fails, locally 63 also fails.

Task is to diagnose and fix this bug.

The following tests FAILED:
         43 - Test User Service (Subprocess aborted)
         63 - Test Hestia Web App (Failed)

43/64 Test #43: Test User Service ...................................Subprocess aborted***Exception:   0.14 sec
Filters: "Test User Service"
Randomness seeded to: 436970649
===============================================================================
All tests passed (4 assertions in 1 test case)

free(): invalid next size (fast)

-------------------------------------------------------------------------------
Test Hestia Web App
-------------------------------------------------------------------------------
/home/cfeller/hestia/test/integration_tests/hestia/TestHestiaWebApp.cc:161
...............................................................................

/home/cfeller/hestia/test/integration_tests/hestia/TestHestiaWebApp.cc:161: FAILED:
  {Unknown expression after the reported line}
due to unexpected exception with message:
  [json.exception.parse_error.101] parse error at line 1, column 1: syntax
  error while parsing value - unexpected end of input; expected '[', '{', or a
  literal