diff --git a/demo/agent_chatbot/run.py b/demo/agent_chatbot/run.py
index 4e6cf36214536..ad8d7906c4a6b 100644
--- a/demo/agent_chatbot/run.py
+++ b/demo/agent_chatbot/run.py
@@ -20,7 +20,7 @@ def interact_with_agent(prompt, history):
     messages = []
     yield messages
     for msg in stream_to_gradio(agent, prompt):
-        messages.append(asdict(msg))
+        messages.append(asdict(msg))  # type: ignore
         yield messages
     yield messages
 
diff --git a/gradio/external.py b/gradio/external.py
index d410dcdce304b..2e2d0ccf76860 100644
--- a/gradio/external.py
+++ b/gradio/external.py
@@ -615,7 +615,7 @@ def load_chat(
         [{"role": "system", "content": system_message}] if system_message else []
     )
 
-    def open_api(message: str, history: list | None) -> str:
+    def open_api(message: str, history: list | None) -> str | None:
         history = history or start_message
         if len(history) > 0 and isinstance(history[0], (list, tuple)):
             history = ChatInterface._tuples_to_messages(history)
@@ -641,7 +641,8 @@ def open_api_stream(
         )
         response = ""
         for chunk in stream:
-            response += chunk.choices[0].delta.content
-            yield response
+            if chunk.choices[0].delta.content is not None:
+                response += chunk.choices[0].delta.content
+                yield response
 
     return ChatInterface(open_api_stream if streaming else open_api, type="messages")
diff --git a/gradio/themes/base.py b/gradio/themes/base.py
index d3ca3dc3a3f17..31d571c49d959 100644
--- a/gradio/themes/base.py
+++ b/gradio/themes/base.py
@@ -124,7 +124,9 @@ def to_dict(self):
         schema = {"theme": {}}
         for prop in dir(self):
             if (
-                not prop.startswith("_") or prop.startswith("_font") or prop in ("_stylesheets", "name")
+                not prop.startswith("_")
+                or prop.startswith("_font")
+                or prop in ("_stylesheets", "name")
             ) and isinstance(getattr(self, prop), (list, str)):
                 schema["theme"][prop] = getattr(self, prop)
         return schema
diff --git a/test/test_utils.py b/test/test_utils.py
index 7b28c101a2a8a..7f60554bc28c6 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -304,7 +304,7 @@ class GenericObject:
         for x in test_objs:
             hints = get_type_hints(x)
             assert len(hints) == 1
-            assert hints["s"] == str
+            assert hints["s"] is str
 
         assert len(get_type_hints(GenericObject())) == 0