Hi @sranjani
Welcome to the Auth0 Community!
Thank you for posting your question, to fix this line of code you will need to adjust the raw variable:
var raw = JSON.stringify({ // Correct JSON structure
"template": "{%- auth0:head -%}{%- auth0:widget -%}"
});
Apart from that I would encourage you to try Auth0 CLI to easily update Page Templates → https://auth0.com/docs/customize/login-pages/universal-login/customize-templates#using-the-auth0-cli-
Thanks
Dawid