sveltekit discord oauth issues

Question

I'm trying to implement discord oauth with sveltekit, but I have stumbled upon some issues. I get this error with callback.js

Property 'query' does not exist on type 'RequestEvent<Record<string, string>>'. Argument of type '{ client_id: string | boolean; client_secret: string | boolean; grant_type: string; redirect_uri: string | boolean; code: any; scope: string; }' is not assignable to parameter of type 'string | Record<string, string> | string[][] | URLSearchParams'. Type '{ client_id: string | boolean; client_secret: string | boolean; grant_type: string; redirect_uri: string | boolean; code: any; scope: string; }' is not assignable to type 'Record<string, string>'. Property 'client_id' is incompatible with index signature. Type 'string | boolean' is not assignable to type 'string'. Type 'boolean' is not assignable to type 'string'.

callback.js

const DISCORD_CLIENT_ID = import.meta.env.VITE_DISCORD_CLIENT_ID;
const DISCORD_CLIENT_SECRET = import.meta.env.VITE_DISCORD_CLIENT_SECRET;
const DISCORD_REDIRECT_URI = import.meta.env.VITE_DISCORD_REDIRECT_URI;

/**
 * @type {import('@sveltejs/kit').RequestHandler}
 */
export async function get({ query }) {
  // fetch returnCode set in the URL parameters.
  const returnCode = query.get('code');
  console.log('returnCode =>', returnCode);

  // initializing data object to be pushed to Discord's token endpoint.
  // the endpoint returns access & refresh tokens for the user.
  const dataObject = {
    client_id: DISCORD_CLIENT_ID,
    client_secret: DISCORD_CLIENT_SECRET,
    grant_type: 'authorization_code',
    redirect_uri: DISCORD_REDIRECT_URI,
    code: returnCode,
    scope: 'identify email guilds'
  };

  // performing a Fetch request to Discord's token endpoint
  const request = await fetch('https://discord.com/api/oauth2/token', {
    method: 'POST',
    body: new URLSearchParams(dataObject),
    headers: { 'Content-Type': 'application/x-www-form-urlencoded' }
  });

  const response = await request.json();

  // redirect to front page in case of error
  if (response.error) {
    console.log('redirect to / due error');
    return {
      headers: { Location: '/' },
      status: 302
    }
  }

  // redirect user to front page with cookies set
  const access_token_expires_in = new Date(Date.now() + response.expires_in); // 10 minutes
  const refresh_token_expires_in = new Date(Date.now() + 30 * 24 * 60 * 60 * 1000); // 30 days
  console.log('redirect to / with cookies');
  return {
    headers: {
      'set-cookie': [
        `disco_access_token=${response.access_token}; Path=/; HttpOnly; SameSite=Strict; Expires=${access_token_expires_in}}`,
        `disco_refresh_token=${response.refresh_token}; Path=/; HttpOnly; SameSite=Strict; Expires=${refresh_token_expires_in}`,
      ],
      Location: '/'
    },
    status: 302
  }
}