Fix infinite recursion in JER code

[blinkseb]

The first commit fix an infinite recursion happening when the code wants to throw an exception.

Second commit update the demo code to add rho to the list of parameters, needed for latest JER payloads.

[cmsbuild]

A new Pull Request was created by @blinkseb (Sébastien Brochet) for CMSSW_8_0_X.

It involves the following packages:

CondFormats/JetMETObjects
JetMETCorrections/Modules

@ggovi, @vadler, @cmsbuild, @davidlange6, @monttj can you please review it and eventually sign? Thanks.
@TaiSakuma, @ahinzmann, @mmarionncern, @rappoccio, @jdolen, @nhanvtran, @apfeiffer1, @schoef, @mariadalfonso this is something you requested to watch as well.
@slava77, @Degano, @smuzaffar you are the release manager for this.

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[diguida]

please test

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/10283/console

[cmsbuild]

+1
Tested at: dd1521b
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12723/10283/summary.html

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-12723/10283/summary.html