fix: handle None response_text in Ollama sequential tool calls

- Add proper None checks before calling .strip() on response_text
- Fixes 'NoneType' object has no attribute 'strip' error with Ollama models
- Ensures backward compatibility by returning empty string instead of None
- Applied fixes in both sync and async versions of get_response methods

Fixes issue #846

Co-authored-by: Mervin Praison <MervinPraison@users.noreply.github.com>

Author: claude[bot]

src/praisonai-agents/praisonaiagents/llm/llm.py

@@ -772,7 +772,7 @@ def get_response(
                                         if formatted_tools and self._supports_streaming_tools():
                                             tool_calls = self._process_tool_calls_from_stream(delta, tool_calls)
 
-                            response_text = response_text.strip()
+                            response_text = response_text.strip() if response_text else ""
 
                             # Create a mock final_response with the captured data
                             final_response = {
@@ -904,7 +904,7 @@ def get_response(
 
                             # Set flag to indicate Ollama was handled
                             ollama_handled = True
-                            final_response_text = response_text.strip()
+                            final_response_text = response_text.strip() if response_text else ""
                             logging.debug(f"[OLLAMA_DEBUG] Ollama follow-up response: {final_response_text[:200]}...")
 
                             # Display the response if we got one
@@ -962,7 +962,7 @@ def get_response(
                         # No tool calls, we're done with this iteration
                         # If we've executed tools in previous iterations, this response contains the final answer
                         if iteration_count > 0:
-                            final_response_text = response_text.strip()
+                            final_response_text = response_text.strip() if response_text else ""
                         break
 
                 except Exception as e:
@@ -993,7 +993,7 @@ def get_response(
                         console=console
                     )
 
-            response_text = response_text.strip()
+            response_text = response_text.strip() if response_text else ""
 
             # Return reasoning content if reasoning_steps is True and we have it
             if reasoning_steps and stored_reasoning_content:
@@ -1155,7 +1155,7 @@ def get_response(
                             if chunk and chunk.choices and chunk.choices[0].delta.content:
                                 response_text += chunk.choices[0].delta.content
 
-                    response_text = response_text.strip()
+                    response_text = response_text.strip() if response_text else ""
                     continue
 
                 except json.JSONDecodeError:
@@ -1464,7 +1464,7 @@ async def get_response_async(
 
                         # Set flag to indicate Ollama was handled
                         ollama_handled = True
-                        final_response_text = response_text.strip()
+                        final_response_text = response_text.strip() if response_text else ""
                         logging.debug(f"[OLLAMA_DEBUG] Ollama follow-up response: {final_response_text[:200]}...")
 
                         # Display the response if we got one
@@ -1571,7 +1571,7 @@ async def get_response_async(
                     # No tool calls, we're done with this iteration
                     # If we've executed tools in previous iterations, this response contains the final answer
                     if iteration_count > 0:
-                        final_response_text = response_text.strip()
+                        final_response_text = response_text.strip() if response_text else ""
                     break
 
             # Handle output formatting
@@ -1808,6 +1808,8 @@ def _handle_ollama_model(self, response_text: str, tool_results: List[Any], mess
 
         # Check if the response is just a JSON tool call
         try:
+            if not response_text:
+                return None
             json_response = json.loads(response_text.strip())
             if not (('name' in json_response or 'function' in json_response) and 
                     not any(word in response_text.lower() for word in ['summary', 'option', 'result', 'found'])):
@@ -2066,7 +2068,8 @@ def response(
                             response_text += content
             else:
                 response = litellm.completion(**completion_params)
-                response_text = response.choices[0].message.content.strip()
+                response_text = response.choices[0].message.content
+                response_text = response_text.strip() if response_text else ""
 
             if verbose:
                 display_interaction(
@@ -2077,7 +2080,7 @@ def response(
                     console=console or self.console
                 )
 
-            return response_text.strip()
+            return response_text.strip() if response_text else ""
 
         except Exception as error:
             display_error(f"Error in response: {str(error)}")
@@ -2154,7 +2157,8 @@ async def aresponse(
                             response_text += content
             else:
                 response = await litellm.acompletion(**completion_params)
-                response_text = response.choices[0].message.content.strip()
+                response_text = response.choices[0].message.content
+                response_text = response_text.strip() if response_text else ""
 
             if verbose:
                 display_interaction(
@@ -2165,7 +2169,7 @@ async def aresponse(
                     console=console or self.console
                 )
 
-            return response_text.strip()
+            return response_text.strip() if response_text else ""
 
         except Exception as error:
             display_error(f"Error in response_async: {str(error)}")