DCS: Fix undefined behavior and invalid pointer access

[davidrohr]

No description provided.

[github-actions]

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[alibuild]

Error while checking build/O2/fullCI_slc9 for 345b923 at 2026-02-11 23:11:

## sw/BUILD/O2-RTC-test-latest/log
[ERROR] Error Opening cagpu library for GPU Tracker (libO2GPUTrackingCUDA.so)
[ERROR] Error: Could not load GPUReconstruction for specified device: CUDA (2)


## sw/BUILD/o2checkcode-latest/log
--
========== List of errors found ==========
++ GRERR=0
++ grep -v clang-diagnostic-error error-log.txt
++ grep ' error:'
++ GRERR=1
++ [[ 1 == 0 ]]
++ mkdir -p /sw/INSTALLROOT/1d3244415b592cecb8ad21072f8e2fbf978db014/slc9_x86-64/o2checkcode/1.0-local241/etc/modulefiles
++ cat
--

Full log here.