Test PythiaConverter_ee_Z_bbbar crashes

### Check duplicate issues.

- [x] Checked for duplicates

### Goal

The test `PythiaConverter_ee_Z_bbbar` crashed in the nightlies. There is probably a small probability that it does (see https://github.com/key4hep/k4SimDelphes/actions/runs/18424378249/job/52503548604, valid for 30 days), since nothing has changed in Delphes or here recently.
This is the stack trace:
```
...
** 749 events processed
** 750 events processed
** 751 events processed
** 752 events processed
** 753 events processed
** 754 events processed
** 755 events processed
** 756 events processed
*** Break *** segmentation violation

===========================================================
There was a crash.
This is the entire stack trace of all threads:
===========================================================
#0 0x00007fb9f94fe7a7 in wait4 () from /lib/x86_64-linux-gnu/libc.so.6
#1 0x00007fb9f94465bb in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#2 0x00007fb9faaf5475 in TUnixSystem::StackTrace() () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-09-21/x86_64-ubuntu24.04-gcc13.3.0-opt/root/6.36.04-3fv74a/lib/root/libCore.so.6.36
#3 0x00007fb9faaf9c24 in TUnixSystem::DispatchSignals(ESignals) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-09-21/x86_64-ubuntu24.04-gcc13.3.0-opt/root/6.36.04-3fv74a/lib/root/libCore.so.6.36
#4
#5 0x00007fb9fb6b880a in SolTrack::KalmanCov(bool, bool, double) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-10-11/x86_64-ubuntu24.04-gcc13.3.0-opt/delphes/4e24ce251ef709ca5b847d858086ca1ec29353f9_develop-s2nscj/lib/libDelphes.so
#6 0x00007fb9fb6a1e05 in ObsTrk::ObsTrk(TVector3, TVector3, double, double, SolGeom*) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-10-11/x86_64-ubuntu24.04-gcc13.3.0-opt/delphes/4e24ce251ef709ca5b847d858086ca1ec29353f9_develop-s2nscj/lib/libDelphes.so
#7 0x00007fb9fb54fd08 in TrackCovariance::Process() () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-10-11/x86_64-ubuntu24.04-gcc13.3.0-opt/delphes/4e24ce251ef709ca5b847d858086ca1ec29353f9_develop-s2nscj/lib/libDelphes.so
#8 0x00007fb9fa9f2577 in TTask::ExecuteTasks(char const*) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-09-21/x86_64-ubuntu24.04-gcc13.3.0-opt/root/6.36.04-3fv74a/lib/root/libCore.so.6.36
#9 0x00007fb9fa9f2077 in TTask::ExecuteTask(char const*) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-09-21/x86_64-ubuntu24.04-gcc13.3.0-opt/root/6.36.04-3fv74a/lib/root/libCore.so.6.36
#10 0x000055ce74dda92e in main ()
===========================================================

The lines below might hint at the cause of the crash. If you see question
marks as part of the stack trace, try to recompile with debugging information
enabled and export CLING_DEBUG=1 environment variable before running.
You may get help by asking at the ROOT forum https://root.cern/forum
preferably using the command (.forum bug) in the ROOT prompt.
Only if you are really convinced it is a bug in ROOT then please submit a
report at https://root.cern/bugs or (preferably) using the command (.gh bug) in
the ROOT prompt. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.
===========================================================
#5 0x00007fb9fb6b880a in SolTrack::KalmanCov(bool, bool, double) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-10-11/x86_64-ubuntu24.04-gcc13.3.0-opt/delphes/4e24ce251ef709ca5b847d858086ca1ec29353f9_develop-s2nscj/lib/libDelphes.so
#6 0x00007fb9fb6a1e05 in ObsTrk::ObsTrk(TVector3, TVector3, double, double, SolGeom*) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-10-11/x86_64-ubuntu24.04-gcc13.3.0-opt/delphes/4e24ce251ef709ca5b847d858086ca1ec29353f9_develop-s2nscj/lib/libDelphes.so
#7 0x00007fb9fb54fd08 in TrackCovariance::Process() () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-10-11/x86_64-ubuntu24.04-gcc13.3.0-opt/delphes/4e24ce251ef709ca5b847d858086ca1ec29353f9_develop-s2nscj/lib/libDelphes.so
#8 0x00007fb9fa9f2577 in TTask::ExecuteTasks(char const*) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-09-21/x86_64-ubuntu24.04-gcc13.3.0-opt/root/6.36.04-3fv74a/lib/root/libCore.so.6.36
#9 0x00007fb9fa9f2077 in TTask::ExecuteTask(char const*) () from /cvmfs/sw-nightlies.hsf.org/key4hep/releases/2025-09-21/x86_64-ubuntu24.04-gcc13.3.0-opt/root/6.36.04-3fv74a/lib/root/libCore.so.6.36
#10 0x000055ce74dda92e in main ()
===========================================================

+ '[' 1 = 1 ']'
+ /k4simdelphes/build/tests/compare_delphes_converter_outputs pythia_converter_output_ee_Z_bbbar.root pythia_converter_output_ee_Z_bbbar_delphes.root
Error in : cannot find tree with name podio_metadata in file pythia_converter_output_ee_Z_bbbar.root
terminate called after throwing an instance of 'std::runtime_error'
what(): File pythia_converter_output_ee_Z_bbbar.root couldn't be found or the "podio_metadata" tree couldn't be read.
/k4simdelphes/tests/testDriver.sh: line 117: 907 Aborted (core dumped) $COMPARE ${OUTPUT_FILE} ${DELPHES_OUTPUT_FILE}
+ seeds_file_cleanup
+ cat /k4simdelphes/build/tests/random_seeds.aFfgvo2T
RANDOM SEED FOR DELPHES CARD = 213
RANDOM SEED FOR PYTHIA CMD = 23077
+ rm /k4simdelphes/build/tests/random_seeds.aFfgvo2T
```

### Operating System and Version

Ubuntu 24.04

### compiler

GCC 13

### The version of the key4hep stack

Nightlies of 2025-10-11

### Package Version

master (b153f969)

### Reproducer

Compile and run the test `PythiaConverter_ee_Z_bbbar`

### Additional context

Previous failure of this test, likely unrelated: https://github.com/key4hep/k4SimDelphes/issues/65

Start by compiling and running the PythiaConverter_ee_Z_bbbar test, then inspect tests/testDriver.sh around line 117 and the compare_delphes_converter_outputs step. Use the reported stack trace in Delphes's TrackCovariance, ObsTrk, and SolTrack::KalmanCov path to identify the crash; done means the test completes and its output comparison succeeds.

Written by the indexing model from the issue text.