Don't let #{application,framework,full}_trace be nil

Those three can be nil when exception backtrace is nil. This happens and
that forced a couple of nil guards in the code. I'm proposing to make
those always return an array, even on nil backtrace.
Merge pull request #17636 from gsamokovarov/exception-wrapper-less-nils

Don't let #{application,framework,full}_trace be nil