Redundant conditional

The previous conditional guarantees that in this block isset($this->instances[$cName]) must be false.  Otherwise we would have returned already.  No point checking it again here.
Merge branch 'hotfix/4919'

Close #4919
Merge pull request #4920 from atz/patch-1

Redundant conditional
Merge branch 'hotfix/4920' into develop

Forward port #4920