Accordion style merge issue fix (#2446)

reflex/vars.py

@@ -436,12 +436,9 @@ class Var:
 
         Returns:
             The merged var.
-
-        Raises:
-            ValueError: If the other value to be merged is None.
         """
         if other is None:
-            raise ValueError("The value to be merged cannot be None.")
+            return self._replace()
         if not isinstance(other, Var):
             other = Var.create(other)
         return self._replace(