add shortcut to success state

src/delta_barth/errors.py

@@ -41,10 +41,17 @@ class StateHandler:
     @property
     def pipe_states(self) -> DataPipeStates:
         assert self._pipe_states is not None, (
-            "tried to access not parsed data pipeline errors"
+            "tried to access not parsed data pipeline states"
         )
         return self._pipe_states
 
+    @property
+    def SUCCESS(self) -> Status:
+        assert self._pipe_states is not None, (
+            "tried to access not parsed data pipeline states"
+        )
+        return self.pipe_states.SUCCESS
+
     def _parse_data_pipe_states(self) -> None:
         if self._pipe_states is not None:
             return