diff --git a/kats/models/bayesian_var.py b/kats/models/bayesian_var.py
index 0279824a..84f15c79 100644
--- a/kats/models/bayesian_var.py
+++ b/kats/models/bayesian_var.py
@@ -442,7 +442,7 @@ def predict(
                     [Y_curr, look_ahead_pred[:, np.newaxis]], axis=1
                 )
 
-            times += ahead_times
+            times += list(ahead_times)
 
         forecast_length = len(times)
 
diff --git a/kats/models/globalmodel/backtester.py b/kats/models/globalmodel/backtester.py
index 2975eca3..f7ee6341 100644
--- a/kats/models/globalmodel/backtester.py
+++ b/kats/models/globalmodel/backtester.py
@@ -438,7 +438,8 @@ def _evaluate(
                 ]
                 ans.extend(tmp_ans)
                 ensemble_fcst = np.median(
-                    np.column_stack(fcst_all[i][k][j] for i in range(n)), axis=1
+                    np.column_stack(fcst_all[i][k][j] for i in range(n)),
+                    axis=1,
                 )
                 evl = eval_func(ensemble_fcst, tmp_actuals)
                 evl["step"] = j
diff --git a/kats/models/metalearner/metalearner_hpt.py b/kats/models/metalearner/metalearner_hpt.py
index 8c03ed79..56d027df 100644
--- a/kats/models/metalearner/metalearner_hpt.py
+++ b/kats/models/metalearner/metalearner_hpt.py
@@ -260,7 +260,7 @@ def __init__(
             )
             # pyre-fixme[4]: Attribute must be annotated.
             self._dim_output_num = (
-                self._target_num.shape[1] if self.numerical_idx else 0
+                self._target_num.shape[1] if self._target_num is not None else 0
             )
             self._get_target_cat()
             self._validate_data()