chore: clearer parsing logic

Signed-off-by: Aaron Pham <29749331+aarnphm@users.noreply.github.com>

src/bentoml/_internal/io_descriptors/json.py

@@ -401,20 +401,21 @@ def parse_dict_to_proto(
     msg: _message.Message,
     json_encoder: type[json.JSONEncoder] = DefaultJsonEncoder,
 ) -> t.Any:
-    # To handle None cases.
-    if obj is not None:
-        from google.protobuf.json_format import ParseDict
-
-        if isinstance(obj, (dict, str, list, float, int, bool)):
-            # ParseDict handles google.protobuf.Struct type
-            # directly if given object has a supported type
-            ParseDict(obj, msg)
-        else:
-            # If given object doesn't have a supported type, we will
-            # use given JSON encoder to convert it to dictionary
-            # and then parse it to google.protobuf.Struct.
-            # Note that if a custom JSON encoder is used, it mustn't
-            # take any arguments.
-            ParseDict(json_encoder().default(obj), msg)
-    # otherwise this function is an identity op for the msg if obj is None.
+    if obj is None:
+        # this function is an identity op for the msg if obj is None.
+        return msg
+
+    from google.protobuf.json_format import ParseDict
+
+    if isinstance(obj, (dict, str, list, float, int, bool)):
+        # ParseDict handles google.protobuf.Struct type
+        # directly if given object has a supported type
+        ParseDict(obj, msg)
+    else:
+        # If given object doesn't have a supported type, we will
+        # use given JSON encoder to convert it to dictionary
+        # and then parse it to google.protobuf.Struct.
+        # Note that if a custom JSON encoder is used, it mustn't
+        # take any arguments.
+        ParseDict(json_encoder().default(obj), msg)
     return msg