Please stop posting offtopic things here. Thank you.

// Main request handler
export default {
  async fetch(request, env) {
    const url = new URL(request.url);
    const secretKey = env.SECRET_KEY; // Defined in the Cloudflare Workers environment
    const apiKey = env.API_KEY;       // Defined in the Cloudflare Workers environment
    // CORS check for allowed domains
    //if (!checkCors(url.origin)) {
    //    return new Response('CORS check failed', { status: 403 });
    //}

    // Handle /v1/signature path
    if (url.pathname === '/v1/signature') {
        const nonce = generateNonce();
        const signature = await generateHMAC(nonce, apiKey, secretKey);

        return new Response(
            JSON.stringify({
                apiKey,
                signature,
                nonce,
            })
            //,
            //{
            //    headers: {
            //        'Content-Type': 'application/json',
            //        'Access-Control-Allow-Origin': "https://connect-example-react.metalpay.com",
            //        'Access-Control-Allow-Methods': 'GET, OPTIONS',
            //    }
            //}
        );
    }
    return env.ASSETS.fetch(request);
  },
}

Error: Failed to publish your Function. Got error: multipart uploads must contain a readable body_part, main_module, or assets