Protection against lumiScale empty collection

[fabiocos]

Protection to prevent a crash if the lumiScale Handle is valid but the collection is empty. Addressing the crash https://hypernews.cern.ch/HyperNews/CMS/get/tier0-Ops/1964.html .
Tested on the failing prompt reco job, it prevents the failure and let the job run (on 100 events).

[cmsbuild]

The code-checks are being triggered in jenkins.

[cmsbuild]

+code-checks

Logs: https://cmssdt.cern.ch/SDT/code-checks/cms-sw-PR-24259/5966

[cmsbuild]

A new Pull Request was created by @fabiocos (Fabio Cossutti) for master.

It involves the following packages:

Calibration/HcalAlCaRecoProducers

@arunhep, @tocheng, @cmsbuild, @franzoni, @pohsun, @lpernie can you please review it and eventually sign? Thanks.
@mmusich, @tocheng this is something you requested to watch as well.
@davidlange6, @slava77, @fabiocos you are the release manager for this.

cms-bot commands are listed here

[fabiocos]

@slava77 @drkovalskyi this protection should prevent the crash observed in SingleMuon prompt reco

[fabiocos]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/29755/console Started: 2018/08/09 15:11

[cmsbuild]

+1
Tested at: 79fedc5
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-24259/29755/summary.html

[cmsbuild]

Comparison job queued.

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-24259/29755/summary.html

Comparison Summary:

• No significant changes to the logs found
• Reco comparison results: 0 differences found in the comparisons
• DQMHistoTests: Total files compared: 31
• DQMHistoTests: Total histograms compared: 2891469
• DQMHistoTests: Total failures: 2
• DQMHistoTests: Total nulls: 0
• DQMHistoTests: Total successes: 2891277
• DQMHistoTests: Total skipped: 190
• DQMHistoTests: Total Missing objects: 0
• DQMHistoSizes: Histogram memory added: 0.0 KiB( 30 files compared)
• Checked 129 log files, 14 edm output root files, 31 DQM output files

[fabiocos]

@lpernie @arunhep unless you have a better suggestion, I would move forward with this protection

[fabiocos]

+1

[fabiocos]

merge

trivial protection against a crash tested to prevent it