Update tools/FinalAnswerTool.py

tools/FinalAnswerTool.py

@@ -17,6 +17,10 @@ class FinalAnswerTool(Tool):
     output_type = "string"
 
     def forward(self, answer: str) -> str:
+        if answer is None:
+        return "NA"
+
+        answer = str(answer)
         match = re.search(r'boxed\{([^}]+)\}', answer)
         if match:
             answer = match.group(1)