Catch case, if value to update with is None

map_machine/util.py

@@ -15,6 +15,8 @@ class MinMax:
 
     def update(self, value: Any) -> None:
         """Update minimum and maximum with new value."""
+        if value is None:
+            return
         self.min_ = value if not self.min_ or value < self.min_ else self.min_
         self.max_ = value if not self.max_ or value > self.max_ else self.max_