See #4854. Don't show IFC mode UI if there is no IFC model.

Still quite a bit of work to be done here, but this is better than nothing.

src/blenderbim/blenderbim/bim/module/geometry/ui.py

@@ -33,6 +33,8 @@ from blenderbim.bim.module.layer.data import LayersData
 
 
 def mode_menu(self, context):
+    if not tool.Ifc.get():
+        return
     row = self.layout.row(align=True)
     if context.scene.BIMGeometryProperties.mode == "EDIT":
         row.operator("bim.override_mode_set_object", icon="CANCEL", text="Discard Changes").should_save = False