use custom exception

reflex/state.py

@@ -71,6 +71,7 @@
  EventHandlerShadowsBuiltInStateMethod,
  ImmutableStateError,
  LockExpiredError,
+ SetUndefinedStateVarError,
 )
 from reflex.utils.exec import is_testing_env
 from reflex.utils.serializers import SerializedType, serialize, serializer
@@ -1218,7 +1219,7 @@ def __setattr__(self, name: str, value: Any):
  value: The value of the attribute.
 
  Raises:
- AttributeError: If a value of a var is set without first defining it.
+ SetUndefinedStateVar: If a value of a var is set without first defining it.
  """
  if isinstance(value, MutableProxy):
  # unwrap proxy objects when assigning back to the state
@@ -1243,7 +1244,7 @@ def __setattr__(self, name: str, value: Any):
  and name not in self.vars
  and name not in self.get_skip_vars()
  ):
- raise AttributeError(
+ raise SetUndefinedStateVarError(
  f"The state variable '{name}' has not been defined in '{type(self).__name__}'. "
  f"All state variables must be declared before they can be set."
  )

reflex/utils/exceptions.py

@@ -111,3 +111,7 @@ class GeneratedCodeHasNoFunctionDefs(ReflexError):
 
 class PrimitiveUnserializableToJSON(ReflexError, ValueError):
  """Raised when a primitive type is unserializable to JSON. Usually with NaN and Infinity."""
+
+
+class SetUndefinedStateVarError(ReflexError, AttributeError):
+ """Raised when setting the value of a var without first declaring it."""