Nodejs Fetch API: unable to verify the first certificate

I'm using the fetch API module in my Philips Hue project and when I make a call to the local ip address (my hub) it produces that error in the title.

const fetch = require('node-fetch');
const gateway = "192.168.0.12";
const username = "username";

let getLights = function(){
    fetch(`https://${gateway}/api/${username}/lights`, {
        method: 'GET'
    }).then((res) => {
        return res.json();
    }).then((json) => {
        console.log(json);
    });
}


module.exports = {getLights};

Any SECURE fix this will eventually go onto the public internet for me to access my lights from anywhere sooo?

It seems like you tried to access it using HTTPS. Most likely on your local network it is going to be HTTP

So by changing https://${gateway}/api/${username}/lights to http://${gateway}/api/${username}/lights should work.

If you're trying to keep it HTTPS then you will have to install a SSL certificate authority onto your network.
These may be useful sources if you're trying to get that done:

https://www.freecodecamp.org/news/how-to-get-https-working-on-your-local-development-environment-in-5-minutes-7af615770eec/

https://letsencrypt.org/docs/certificates-for-localhost/