Move resolve ensemble class check to init

Author: eddiebergman

autosklearn/estimators.py

@@ -405,7 +405,12 @@ def __init__(
         )
 
         # Need to resolve the ensemble class here so we can act on it below.
-        ensemble_class = self.resolve_ensemble_class(ensemble_class, metric)
+        if ensemble_class == "default":
+            ensemble_class = (
+                MultiObjectiveDummyEnsemble
+                if isinstance(metric, Scorer) and len(metric) > 1
+                else EnsembleSelection
+            )
         self.ensemble_class = ensemble_class
 
         # User specified `ensemble_size` explicitly, warn them about deprecation
@@ -742,15 +747,6 @@ def fit_ensemble(
         )
         return self
 
-    def resolve_ensemble_class(self, ensemble_class, metric):
-        if ensemble_class == "default":
-            ensemble_class = (
-                EnsembleSelection
-                if metric is None or isinstance(metric, Scorer) or len(metric) == 1
-                else MultiObjectiveDummyEnsemble
-            )
-        return ensemble_class
-
     def refit(self, X, y):
         """Refit all models found with fit to new data.