Not able to login the page with okta using Angularjs

i have created the simple login page using angularjs integrate with okta api(https://dev-498575.oktapreview.com/api/v1/authn) this post api i am passing the parameters like:
1)Username
2)password
3)option:multiOptionalFactorEnroll:true
warnBeforePasswordExpired:true

its throwing the 500 internal server error,can you help me how to fix this issue?

Send a note to developers@okta.com - this will require more troubleshooting