This type of tool only works on wires

src/Mod/Draft/Draft.py

@@ -1376,6 +1376,8 @@ def joinTwoWires(wire1, wire2):
     return True
 
 def split(wire, newPoint, edgeIndex):
+    if getType(wire) != "Wire":
+        return
     wire1Points = []
     wire2Points = []
     for index, point in enumerate(wire.Points):

src/Mod/Draft/DraftTools.py

@@ -3262,7 +3262,6 @@ class Split(Modifier):
             getPoint(self, arg)
             redraw3DView()
         elif arg["Type"] == "SoMouseButtonEvent" and arg["State"] == "DOWN" and arg["Button"] == "BUTTON1":
-            print('clicky!')
             self.point, ctrlPoint, info = getPoint(self, arg)
             if "Edge" in info["Component"]:
                 return self.proceed(info)