fix: LC2ST kwarg defaults type hints (#1565)

* fix kwarg typing

* fix if else logic

* fix init bugs

Author: janfb

sbi/diagnostics/lc2st.py

@@ -123,12 +123,12 @@ def __init__(
                     'or a valid scikit-learn classifier class.'
                 )
         assert issubclass(classifier, BaseEstimator), (
-            "classifier must be a subclass of sklearn's BaseEstimator"
+            "classier must either be a string or a subclass of BaseEstimator."
         )
         self.clf_class = classifier
 
-        self.clf_kwargs = classifier_kwargs
-        if self.clf_kwargs is None:
+        # for MLPClassifier, set default parameters
+        if classifier_kwargs is None:
             if self.clf_class == MLPClassifier:
                 ndim = thetas.shape[-1]
                 self.clf_kwargs = {
@@ -140,7 +140,7 @@ def __init__(
                     "n_iter_no_change": 50,
                 }
             else:
-                self.clf_kwargs = {}
+                self.clf_kwargs: Dict[str, Any] = {}
 
         # initialize classifiers, will be set after training
         self.trained_clfs = None
@@ -269,7 +269,7 @@ def train_on_observed_data(
         if seed is not None:
             if "random_state" in self.clf_kwargs:
                 print("WARNING: changing the random state of the classifier.")
-            self.clf_kwargs["random_state"] = seed  # type: ignore
+            self.clf_kwargs["random_state"] = seed
 
         # train the classifier
         trained_clfs = self._train(