How does fallback_interceptor works?

[Makoish]

Hello, I am trying to implement something using playwright MCP, sometimes this error happens [Cannot read property innerText](https://stackoverflow.com/questions/63367277/cannot-read-property-innertext-of-null-for-valid-selector-using-playwright) I want to ignore this error when it happens because it closes the session while I want to continue the navigation. I found https://docs.langchain.com/oss/python/langchain/mcp#writing-interceptors that I guess is the solution to my issue but it's not working probably with me so I guess I am doing something wrong

async def fallback_interceptor(
    request: MCPToolCallRequest,
    handler,
):
    """Return a fallback value if tool execution fails."""

    raise ValueError()
    try:
        return await handler(request)
    except Exception as e:
        
        return f"Tool {request.name} timed out. Ignore it and continue navigation"

  try:
        mcp_client = MultiServerMCPClient(connections=PLAYWRIGHT_MCP_CONNECTION, tool_interceptors=[fallback_interceptor])
        async with mcp_client.session("playwright") as session:
            available_tools: List[BaseTool] = await load_mcp_tools(session)
            llm = init_chat_model(
                model=LLM_MODEL_NAME, 
                model_provider="google_genai", 
                google_api_key=os.getenv("GOOGLE_KEY")
            )