diff -r a13da70a8ae4 -r 4a08728a2ea4 graphics/LD_Objects.py
--- a/graphics/LD_Objects.py	Tue Oct 19 13:09:45 2021 +0200
+++ b/graphics/LD_Objects.py	Wed Oct 20 08:57:07 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: