diff --git a/autoPyTorch/api/base_task.py b/autoPyTorch/api/base_task.py
index afc128625..427522beb 100644
--- a/autoPyTorch/api/base_task.py
+++ b/autoPyTorch/api/base_task.py
@@ -174,7 +174,7 @@ def __init__(
         self._logger: Optional[PicklableClientLogger] = None
         self.run_history: RunHistory = RunHistory()
         self.trajectory: Optional[List] = None
-        self.dataset_name: Optional[str] = None
+        self.dataset_name: str = ""
         self.cv_models_: Dict = {}
         self.experiment_task_name: str = 'runSearch'
 
@@ -702,6 +702,7 @@ def _run_traditional_ml(self) -> None:
             self._stopwatch.start_task(traditional_task_name)
             elapsed_time = self._stopwatch.wall_elapsed(self.dataset_name)
 
+            assert self._func_eval_time_limit_secs is not None
             time_for_traditional = int(
                 self._total_walltime_limit - elapsed_time - self._func_eval_time_limit_secs
             )
@@ -709,9 +710,10 @@ def _run_traditional_ml(self) -> None:
             self._stopwatch.stop_task(traditional_task_name)
 
     def _run_ensemble(self, dataset: BaseDataset, optimize_metric: str,
-                      precision: int) -> EnsembleBuilderManager:
+                      precision: int) -> Optional[EnsembleBuilderManager]:
 
         assert self._logger is not None
+        assert self._metric is not None
 
         elapsed_time = self._stopwatch.wall_elapsed(self.dataset_name)
         time_left_for_ensembles = max(0, self._total_walltime_limit - elapsed_time)
@@ -788,7 +790,7 @@ def _start_smac(self, proc_smac: AutoMLSMBO) -> None:
             except Exception as e:
                 self._logger.warning(f"Could not save {trajectory_filename} due to {e}...")
 
-    def _run_smac(self, dataset: BaseDataset, proc_ensemble: EnsembleBuilderManager,
+    def _run_smac(self, dataset: BaseDataset, proc_ensemble: Optional[EnsembleBuilderManager],
                   budget_type: Optional[str] = None, budget: Optional[float] = None,
                   get_smac_object_callback: Optional[Callable] = None,
                   smac_scenario_args: Optional[Dict[str, Any]] = None) -> None:
@@ -805,6 +807,9 @@ def _run_smac(self, dataset: BaseDataset, proc_ensemble: EnsembleBuilderManager,
             self._logger.warning(" Could not run SMAC because there is no time left")
         else:
             budget_config = self._get_budget_config(budget_type=budget_type, budget=budget)
+
+            assert self._func_eval_time_limit_secs is not None
+            assert self._metric is not None
             proc_smac = AutoMLSMBO(
                 config_space=self.search_space,
                 dataset_name=dataset.dataset_name,
@@ -1095,7 +1100,7 @@ def refit(
         Returns:
             self
         """
-        if self.dataset_name is None:
+        if self.dataset_name == "":
             self.dataset_name = str(uuid.uuid1(clock_seq=os.getpid()))
 
         if self._logger is None:
@@ -1165,7 +1170,7 @@ def fit(self,
         Returns:
             (BasePipeline): fitted pipeline
         """
-        if self.dataset_name is None:
+        if self.dataset_name == "":
             self.dataset_name = str(uuid.uuid1(clock_seq=os.getpid()))
 
         if self._logger is None: