qtvcp -nurbs_editor: remove unused function call

copied over from example code, but never utilized

Author: c-morley

lib/python/qtvcp/widgets/nurbs_editor.py

@@ -300,7 +300,7 @@ def report_gcode_error(self, result, seq, filename):
     elif len(sys.argv) == 2:
         inifilename = sys.argv[1]
     else:
-        usage()
+        sys.exit(1)
     window = NurbsEditor(path = inifilename)
     window.load_dialog()
     sys.exit(app.exec_())