self.var contains all the info we need

reflex/state.py

@@ -1277,8 +1277,10 @@ class BaseState(Base, ABC, extra=pydantic.Extra.allow):
             self._mark_dirty()
             return
 
-        if not name in self.vars and not name in self._computed_var_dependencies and not name in self.get_skip_vars():
-            raise AttributeError(f"The state var '{name}' has not been defined in '{type(self).__name__}'. All state vars must be declared before they can be set.")
+        if name not in self.vars and name not in self.get_skip_vars():
+            raise AttributeError(
+                f"The state var '{name}' has not been defined in '{type(self).__name__}'. All state vars must be declared before they can be set."
+            )
 
         # Set the attribute.
         super().__setattr__(name, value)

tests/units/test_state.py

@@ -3265,7 +3265,8 @@ def test_child_mixin_state() -> None:
 
 
 def test_assignment_to_undeclared_vars():
-    """Test that an attribute error is thrown when undeclared vars are set"""
+    """Test that an attribute error is thrown when undeclared vars are set."""
+
     class State(BaseState):
         val: str
 
@@ -3273,7 +3274,6 @@ def test_assignment_to_undeclared_vars():
             self.num = 5
 
     class Substate(State):
-
         def handle_var(self):
             self.value = 20
 
@@ -3285,3 +3285,6 @@ def test_assignment_to_undeclared_vars():
 
     with pytest.raises(AttributeError):
         sub_state.handle()
+
+    with pytest.raises(AttributeError):
+        sub_state.handle_var()