OSLShaderUI : Fix support for "null" widget type
OSLShaderUI : Fix support for "null" widget type

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