ITS: fix ITSTrackROF outpu

[f3sch]

Fixes crash if there were clusters but the ITS tracking did not find anything, the tpcits matching still wants ITSTrackROF to be correct, otherwise as reported by @catalinristea and @shahor02:

[29475:itstpc-track-matcher]: [10:19:47][INFO] Updating TPC VDrift: corrFact 1.0001795 wrt refVDrift 2.621143 and DriftTimeOffset correction 0 wrt 1.4877396 from source TPCITSTgl
[29475:itstpc-track-matcher]: libc++abi: terminating
[29475:itstpc-track-matcher]: *** Program crashed (Abort trap: 6)
[29475:itstpc-track-matcher]: Backtrace by DPL:
[29475:itstpc-track-matcher]:     1   libsystem_platform.dylib            0x000000018a0b57a4: _sigtramp
[29475:itstpc-track-matcher]:     2   libsystem_pthread.dylib             0x000000018a0ab8d8: pthread_kill
[29475:itstpc-track-matcher]:     3   libsystem_c.dylib                   0x0000000189fb2790: abort

now:

[32300:itstpc-track-matcher]: [10:21:56][INFO] Validated 0 matches out of 0 for 77220 TPC and 0 ITS tracks in 1 iterations
[32300:itstpc-track-matcher]: [10:21:56][INFO] AfterBurner will check 1650542 seeds from 73935 TPC tracks and 1419 interaction candidates with 2 threads
[32300:itstpc-track-matcher]: [10:21:56][INFO] Failed 0 TPC-ITS refits out of 0
[32300:itstpc-track-matcher]: [10:21:56][INFO] AfterBurner validated 304 tracks

Also checked that ITSTrackROF in case something was found, is still the same as before.

[shahor02]

Thanks @f3sch

Could you also add

diff --git a/Detectors/GlobalTracking/src/MatchTPCITS.cxx b/Detectors/GlobalTracking/src/MatchTPCITS.cxx
index 29c45edd6e..1457790c7c 100644
--- a/Detectors/GlobalTracking/src/MatchTPCITS.cxx
+++ b/Detectors/GlobalTracking/src/MatchTPCITS.cxx
@@ -709,7 +709,7 @@ bool MatchTPCITS::prepareITSData()
   mITSWork.reserve(mITSTracksArray.size());
 
   // total N ITS clusters in TF
-  const auto& lastClROF = mITSClusterROFRec[nROFs - 1];
+  const auto& lastClROF = mITSClusterROFRec.back();
   int nITSClus = lastClROF.getFirstEntry() + lastClROF.getNEntries();
   mABClusterLinkIndex.resize(nITSClus, MinusOne);
   for (int sec = o2::constants::math::NSectors; sec--;) {

to make the matcher internally consistent.

[f3sch]

sure done

[shahor02]

Tested locally, merging.