diff -r e6c758e41f82 -r dd49e4055a10 graphics/LD_Objects.py
--- a/graphics/LD_Objects.py	Thu Sep 16 09:40:36 2021 +0200
+++ b/graphics/LD_Objects.py	Wed Oct 06 10:45:06 2021 +0200
@@ -405,6 +405,8 @@
             if self.Value is None:
                 self.Value = False
             spreading = self.Input.ReceivingCurrent()
+            if spreading == "undefined":
+                spreading = False
             if self.Type == CONTACT_NORMAL:
                 spreading &= self.Value
             elif self.Type == CONTACT_REVERSE: