CORS error in Firefox

[TheNoceboEffect]

I am developing a Scratch extension, and when trying to use the Web Audio API in my code, I encountered a CORS error, and I originally used the code : "myFirstBlock ({ MY_STRING }) {
function loadSound(url) {
return fetch(url)
.then(response => response.arrayBuffer())
.then(arrayBuffer => audioContext.decodeAudioData(arrayBuffer));
}

    function playSound(audioBuffer) {
        const soundSource = audioContext.createBufferSource();
        soundSource.buffer = audioBuffer;
        soundSource.connect(audioContext.destination);
        soundSource.start();
        AudioContext().resume();
    }
    const baseURL = 'https://www./github.com/TheNoceboEffect/audiotesting2/raw/master/sounds/';
    const soundURL = `${baseURL}${MY_STRING}${fileExtension};`
    const fileExtension = '.wav'
}

}

module.exports = Scratch3YourExtension;" in my code, however when trying to fix the CORS errors I received ([Error] Fetch API cannot load https://github.com/TheNoceboEffect/audiotesting/raw/master/sounds/[object%20Object]undefined; due to access control checks.
[Error] Failed to load resource: Origin https://bug-free-journey-5jg9rwqppvw3pv5w-8000.app.github.dev/ is not allowed by Access-Control-Allow-Origin. Status code: 404 ([object Object]undefined;, line 0)[Error] Not allowed to load local resource: blob://nullhttps//bug-free-journey-5jg9rwqppvw3pv5w-8000.app.github.dev/4f46f43b64af7fd567fc.worker.js.map), using the code "myFirstBlock ({ MY_STRING }) {
function loadSound(url) {
return fetch(url)
.then(response => response.arrayBuffer())
.then(arrayBuffer => audioContext.decodeAudioData(arrayBuffer));
}

    function playSound(audioBuffer) {
        const soundSource = audioContext.createBufferSource();
        soundSource.buffer = audioBuffer;
        soundSource.connect(audioContext.destination);
        soundSource.start();
        AudioContext().resume();
    }
    const baseURL = 'https://www./github.com/TheNoceboEffect/audiotesting/raw/master/sounds/';
    const soundURL = `${baseURL}${MY_STRING}${fileExtension};`
    const fileExtension = '.wav'

    loadSound(soundURL).then(playSound);
    headers: new Headers({
        "Access-Control-Allow-Origin": "http://localhost:3000",
        "Access-Control-Allow-Methods": "GET",
        "Access-Control-Allow-Headers": "Content-Type, Origin, Accept",
        "Access-Control-Max-Age": "86400",
    })
    const xhr = new XMLHttpRequest();
    xhr.open("GET", "url", true);
    xhr.withCredentials = true;
    xhr.send(null);
}

}

module.exports = Scratch3YourExtension;" to play sounds in my extension, however I received the errors "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://www./github.com/TheNoceboEffect/audiotesting/raw/master/sounds/aundefined;. (Reason: CORS request did not succeed). Status code: (null)." and "Uncaught (in promise) TypeError: NetworkError when attempting to fetch resource." in Firefox. I also made sure to put "const audioContext = new (window.AudioContext || window.webkitAudioContext)();" at the top of my code to define the audio context for the API I was using, the Web Audio API.

Does anyone know how to fix this error?