Replace cryptic assert with informative exception for missing Wrapper dictionary

[wmtan]

If an attempt is made to produce a product whose wrapped class (edm::Wrapper) does not have a dictionary, a cryptic assert resulted. This cryptic assert could also occur for other reasons.
This simple PR replaces the cryptic assert with an informative exception, which in the above case is a missing dictionary exception. This PR also fixes another minor problem. If TypeWithDict::name() or any related function was used to get the name of a class that has no dictionary, "dummyType" was returned, rather than the correct name of the class.
This problem is ROOT6 specific, but it also occurs in CMSSW_7_5_X. This fix can be back ported to 7_5_X if needed. This problem does not directly affect 7_4_X.

[cmsbuild]

A new Pull Request was created by @wmtan for CMSSW_7_6_X.

Replace cryptic assert with informative exception for missing Wrapper dictionary

It involves the following packages:

FWCore/Utilities

@cmsbuild, @smuzaffar, @Dr15Jones can you please review it and eventually sign? Thanks.
@makortel, @Martin-Grunewald, @wddgit this is something you requested to watch as well.
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@Degano you are the release manager for this.
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[Dr15Jones]

please test

[Dr15Jones]

+1

[cmsbuild]

The tests are being triggered in jenkins.
https://cmssdt.cern.ch/jenkins/job/ib-any-integration/8711/console

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs after it passes the integration tests. This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[cmsbuild]

+1
Tested at: e008ef8
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11703/8711/summary.html

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[cmsbuild]

Comparison is ready
https://cmssdt.cern.ch/SDT/jenkins-artifacts/pull-request-integration/PR-11703/8711/summary.html

[cmsbuild]

This pull request is fully signed and it will be integrated in one of the next CMSSW_7_6_X IBs (tests are also fine). This pull request requires discussion in the ORP meeting before it's merged. @davidlange6, @Degano, @smuzaffar

[davidlange6]

+1