Fix: Send tool_calls in Google streaming responses

Changed line 511 to check list length instead of boolean evaluation.
This fixes the bug where tool calls extracted from Google chunks were not being
sent to clients because empty lists were being treated as falsy.

Before: 'tool_calls': delta_tool_calls if delta_tool_calls else None
After:  'tool_calls': delta_tool_calls if len(delta_tool_calls) > 0 else None

aisbf/handlers.py

@@ -481,6 +481,7 @@ class RequestHandler:
                                 if tool_call["id"] not in seen_tool_call_ids:
                                     delta_tool_calls.append(tool_call)
                                     seen_tool_call_ids.add(tool_call["id"])
+                                    logger.info(f"Adding tool call to delta: {tool_call}")
                             
                             # Check if this is the last chunk
                             is_last_chunk = (chunk_idx == total_chunks - 1)
@@ -507,7 +508,7 @@ class RequestHandler:
                                             "content": delta_text if delta_text else "",
                                             "refusal": None,
                                             "role": "assistant",
-                                            "tool_calls": delta_tool_calls if delta_tool_calls else None
+                                            "tool_calls": delta_tool_calls if len(delta_tool_calls) > 0 else None
                                         },
                                         "finish_reason": chunk_finish_reason,
                                         "logprobs": None,