Fix #975. Add error message if drawing not created when adding to sheet

src/ifcblenderexport/blenderbim/bim/operator.py

@@ -2271,9 +2271,12 @@ class AddDrawingToSheet(bpy.types.Operator):
         props = bpy.context.scene.DocProperties
         sheet_builder = sheeter.SheetBuilder()
         sheet_builder.data_dir = bpy.context.scene.BIMProperties.data_dir
-        sheet_builder.add_drawing(
-            props.drawings[props.active_drawing_index].name,
-            props.sheets[props.active_sheet_index].name)
+        try:
+            sheet_builder.add_drawing(
+                props.drawings[props.active_drawing_index].name,
+                props.sheets[props.active_sheet_index].name)
+        except:
+            self.report({'ERROR'}, 'Drawings need to be created before being added to a sheet')
         return {'FINISHED'}
 
 

src/ifcblenderexport/blenderbim/bim/sheeter.py

@@ -43,6 +43,9 @@ class SheetBuilder:
         sheet_path = os.path.join(self.data_dir, 'sheets', sheet_name + '.svg')
         view_path = os.path.join(self.data_dir, 'diagrams', view_name + '.svg')
 
+        if not os.path.isfile(view_path):
+            raise FileNotFoundError
+
         ET.register_namespace('', 'http://www.w3.org/2000/svg')
         ET.register_namespace('xlink', 'http://www.w3.org/1999/xlink')