Implement property iteration on BRM!

src/ert/run_models/iterated_ensemble_smoother.py

@@ -65,6 +65,14 @@ def __init__(
         # It is initialized later, but kept track of here
         self.sies_smoother = None
 
+    @property
+    def iteration(self) -> int:
+        """Returns the SIES iteration number, starting at 1."""
+        if self.sies_smoother is None:
+            return 1
+        else:
+            return self.sies_smoother.iteration
+
     def analyzeStep(
         self,
         prior_storage: EnsembleAccessor,
@@ -182,8 +190,7 @@ def run_experiment(
                     current_iter - 1,
                 )
 
-                assert self.sies_smoother is not None, "smoother must be initialized"
-                analysis_success = current_iter < self.sies_smoother.iteration
+                analysis_success = current_iter < self.iteration
                 if analysis_success:
                     update_success = True
                     break