fix: check if strat col for evaluate model

LoopStructural/modelling/core/geological_model.py

@@ -1539,6 +1539,9 @@ def evaluate_model(self, xyz: np.ndarray, scale: bool = True) -> np.ndarray:
         strat_id = np.zeros(xyz.shape[0], dtype=int)
         # set strat id to -1 to identify which areas of the model aren't covered
         strat_id[:] = -1
+        if self.stratigraphic_column is None:
+            logger.warning("No stratigraphic column defined")
+            return strat_id
         for group in reversed(self.stratigraphic_column.keys()):
             if group == "faults":
                 continue