Added check for unknown tool names (#1924)

* answer.py

* Let it continue if broken

backend/danswer/llm/answering/answer.py

@@ -240,9 +240,22 @@ def _raw_output_for_explicit_tool_calling_llms(
         # if we have a tool call, we need to call the tool
         tool_call_requests = tool_call_chunk.tool_calls
         for tool_call_request in tool_call_requests:
-            tool = [
+            known_tools_by_name = [
                 tool for tool in self.tools if tool.name == tool_call_request["name"]
-            ][0]
+            ]
+
+            if not known_tools_by_name:
+                logger.error(
+                    "Tool call requested with unknown name field. \n"
+                    f"self.tools: {self.tools}"
+                    f"tool_call_request: {tool_call_request}"
+                )
+                if self.tools:
+                    tool = self.tools[0]
+                else:
+                    continue
+            else:
+                tool = known_tools_by_name[0]
             tool_args = (
                 self.force_use_tool.args
                 if self.force_use_tool.tool_name == tool.name