Check if there is a mainwindow to prevent crash
Fixes a crash that occurs when SMTK is initialized without creating a main window. This is mostly applicable when creating unit tests.
FYI: @bob.obara @dcthomp
Fixes a crash that occurs when SMTK is initialized without creating a main window. This is mostly applicable when creating unit tests.
FYI: @bob.obara @dcthomp