OSLObjectUI.PlugAdder : Fix exception with unsupported plug types
OSLObjectUI.PlugAdder : Fix exception with unsupported plug types

lucienfostier/gaffer,andrewkaufman/gaffer,boberfly/gaffer,johnhaddon/gaffer,GafferHQ/gaffer,appleseedhq/gaffer,johnhaddon/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,ImageEngine/gaffer,johnhaddon/gaffer,hradec/gaffer,boberfly/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,appleseedhq/gaffer,GafferHQ/gaffer,lucienfostier/gaffer,boberfly/gaffer,hradec/gaffer,ImageEngine/gaffer,GafferHQ/gaffer,andrewkaufman/gaffer,appleseedhq/gaffer,appleseedhq/gaffer,hradec/gaffer,ImageEngine/gaffer,lucienfostier/gaffer,boberfly/gaffer,hradec/gaffer,andrewkaufman/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer,hradec/gaffer,andrewkaufman/gaffer,johnhaddon/gaffer