Handle None content in stop-sequence trimming (#1826)

Author: chahn

src/smolagents/models.py

@@ -74,8 +74,15 @@ def convert(obj):
     return convert(obj)
 
 
-def remove_content_after_stop_sequences(content: str, stop_sequences: list[str]) -> str:
-    """Remove content after any stop sequence is encountered."""
+def remove_content_after_stop_sequences(content: str | None, stop_sequences: list[str] | None) -> str | None:
+    """Remove content after any stop sequence is encountered.
+
+    Some providers may return ``None`` content (for example when responding purely with tool calls),
+    so we skip processing in that case.
+    """
+    if content is None or not stop_sequences:
+        return content
+
     for stop_seq in stop_sequences:
         split = content.split(stop_seq)
         content = split[0]

tests/test_models.py

@@ -724,6 +724,17 @@ def test_remove_content_after_stop_sequences():
     assert removed_content == "Hello"
 
 
+def test_remove_content_after_stop_sequences_handles_none():
+    # Test with None stop sequence
+    content = "Hello world!"
+    removed_content = remove_content_after_stop_sequences(content, None)
+    assert removed_content == content
+
+    # Test with None content
+    removed_content = remove_content_after_stop_sequences(None, ["<code>"])
+    assert removed_content is None
+
+
 @pytest.mark.parametrize(
     "convert_images_to_image_urls, expected_clean_message",
     [