fix: resolve OutputParserException when using Ollama instead of Gemini

libs/partners/ollama/langchain_ollama/chat_models.py

@@ -103,6 +103,13 @@ def _parse_json_string(
         OutputParserException: If the string is invalid and ``skip=False``.
 
     """
+    # Handle empty strings gracefully
+    if not json_string.strip():
+        if skip:
+            return json_string
+        # Return empty dict for empty strings in tool calls
+        return {}
+
     try:
         return json.loads(json_string)
     except json.JSONDecodeError:
@@ -939,6 +946,21 @@ def _iterate_over_stream(
                     )
                     continue
 
+                # Handle structured output scenarios where content might be empty
+                # but tool_calls are present
+                has_tool_calls = "message" in stream_resp and stream_resp[
+                    "message"
+                ].get("tool_calls")
+
+                # Skip empty content chunks unless they have tool
+                #  calls or are final chunks
+                if (
+                    not content.strip()
+                    and not has_tool_calls
+                    and not stream_resp.get("done")
+                ):
+                    continue
+
                 if stream_resp.get("done") is True:
                     generation_info = dict(stream_resp)
                     if "model" in generation_info: