protect HGCDigitizer from crashing when simHitAccumulator is empty

[mmusich]

resolves #29274

PR description:

Solves the problem reported at: #29274 by implementing the suggestion from @makortel at #29274 (comment).

PR validation:

Tested the code changes with runTheMatrix.py --what upgrade -l 20610.99 in CMSSW_11_1_X_2020-03-23-2300, which now runs to completion.

if this PR is a backport please specify the original PR and why you need to backport that PR:

Not a backport.

[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-29286/14346

• This PR adds an extra 16KB to repository

[cmsbuild]

A new Pull Request was created by @mmusich (Marco Musich) for master.

It involves the following packages:

SimCalorimetry/HGCalSimProducers

@cmsbuild, @civanch, @kpedro88, @mdhildreth can you please review it and eventually sign? Thanks.
@vandreev11, @sethzenz, @makortel, @rovere, @lgray, @cseez, @apsallid, @pfs, @deguio, @hatakeyamak this is something you requested to watch as well.
@davidlange6, @silviodonato, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[makortel]

@cmsbuild, please test workflow 20661.97, 20634.99

[cmsbuild]

The tests are being triggered in jenkins.
Test Parameters:

• MATRIX_EXTRAS = 20634.99,20661.97
  https://cmssdt.cern.ch/jenkins/job/ib-run-pr-tests/5349/console Started: 2020/03/24 15:04

[cmsbuild]

+1
Tested at: 90d886c
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-e30fab/5349/summary.html
CMSSW: CMSSW_11_1_X_2020-03-24-1100
SCRAM_ARCH: slc7_amd64_gcc820

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-e30fab/5349/summary.html

@slava77 comparisons for the following workflows were not done due to missing matrix map:

• /data/cmsbld/jenkins/workspace/compare-root-files-short-matrix/data/PR-e30fab/20634.99_TTbar_14TeV+TTbar_14TeV_TuneCP5_2026D41PU_GenSimHLBeamSpotFull14+PREMIX_2026D41PU_PremixHLBeamSpotFull14PU_Premix+DigiFullTriggerPUPRMXCombined_2026D41PU+RecoFullGlobalPUPRMX_2026D41PU+HARVESTFullGlobalPU_2026D41PU
• /data/cmsbld/jenkins/workspace/compare-root-files-short-matrix/data/PR-e30fab/20661.97_PREMIXUP26D41_PU25+PREMIX_2026D41PU_PremixHLBeamSpotFullPU_Premix

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 34
• DQMHistoTests: Total histograms compared: 2692493
• DQMHistoTests: Total failures: 29
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2692145
• DQMHistoTests: Total skipped: 319
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 33 files compared)
• Checked 147 log files, 16 edm output root files, 34 DQM output files

[civanch]

+1

[kpedro88]

+upgrade

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next master IBs (tests are also fine). This pull request will now be reviewed by the release team before it's merged. @davidlange6, @silviodonato, @fabiocos (and backports should be raised in the release meeting by the corresponding L2)

[silviodonato]

+1