diff --git a/docs/source/conf.py b/docs/source/conf.py
index 7efebfb8d2..324be8a0fd 100644
--- a/docs/source/conf.py
+++ b/docs/source/conf.py
@@ -106,7 +106,6 @@ def generate_apidocs(*args):
 # html_theme_path = [sphinx_rtd_theme.get_html_theme_path()]
 html_theme_options = {
     "external_links": [{"url": "https://github.com/Project-MONAI/tutorials", "name": "Tutorials"}],
-    "collapse_navigation": True,
     "icon_links": [
         {
             "name": "GitHub",
diff --git a/monai/data/csv_saver.py b/monai/data/csv_saver.py
index c79cd1016a..62f407bfd5 100644
--- a/monai/data/csv_saver.py
+++ b/monai/data/csv_saver.py
@@ -87,7 +87,6 @@ def save(self, data: Union[torch.Tensor, np.ndarray], meta_data: Optional[Dict]
         """
         save_key = meta_data[Key.FILENAME_OR_OBJ] if meta_data else str(self._data_index)
         self._data_index += 1
-        data_: np.ndarray
         if isinstance(data, torch.Tensor):
             data = data.detach().cpu().numpy()
         self._cache_dict[save_key] = np.asarray(data, dtype=float)
diff --git a/monai/engines/workflow.py b/monai/engines/workflow.py
index 4e1834a625..de3e00c83e 100644
--- a/monai/engines/workflow.py
+++ b/monai/engines/workflow.py
@@ -149,6 +149,7 @@ def set_sampler_epoch(engine: Engine):
         self.prepare_batch = prepare_batch
         self.metric_cmp_fn = metric_cmp_fn
         self.amp = amp
+        self.scaler = None
 
         if event_names is None:
             event_names = [IterationEvents]
diff --git a/monai/transforms/io/array.py b/monai/transforms/io/array.py
index 2c1a3c89ff..a8e9ed1e7c 100644
--- a/monai/transforms/io/array.py
+++ b/monai/transforms/io/array.py
@@ -45,7 +45,7 @@ def switch_endianness(data, new="<"):
     """
     if isinstance(data, np.ndarray):
         # default to system endian
-        sys_native = ((sys.byteorder == "little") and "<") or ">"
+        sys_native = "<" if (sys.byteorder == "little") else ">"
         current_ = sys_native if data.dtype.byteorder not in ("<", ">") else data.dtype.byteorder
         if new not in ("<", ">"):
             raise NotImplementedError(f"Not implemented option new={new}.")