I am trying to Catch an Error of my Fetch Function.

ive tried to catch my function with this:

updateState() {
    fetch('http://127.0.0.1:3333/xxx')
        .then((res) => res.json())
        .then((json) => {
                this.setState(() => {
                    return {
                        lightState: json.value
                    }
                });
            }
        ).catch(function () {
        console.log("error");
    });
}

but i still get the Errormessage in the console

PS: In the Console i also get the "error" from the catch function. But the ERR_CONNECTION_REFUSED error still comes up