no error for incorrect data example

When I ran the example code https://docs.fastht.ml/tutorials/quickstart_for_web_devs.html#variables-in-urls and tried the example URL with incorrect data [127.0.0.1:5001/uma/five](http://127.0.0.1:5001/uma/five), I get a page containing the text `/uma/five` rather than an error.