Why error 500 response in pterodactyl api?

Question

I'm making a system that could create a pterodactyl user account with the given variable. I used the fetch function(POST) in js to create the request. But whenever it submits, an error 500 appears in the console log. I'm just wondering how to fix it

Code:

fetch('https://corsproxy.io/?' + encodeURIComponent('https://servers.chynodes.xyz/api/application/users'), {
            "method": "POST",
            "headers": {
                "Accept": "application/json",
                "Content-Type": "application/json",
                "Authorization": "Bearer api_key", //i replaced the api key with that for safety reasons
                "cookie": "pterodactyl_session=eyJpdiI6ImlHS1Y5VGdPTXJPb2FMVDRBYWw3Y3c9PSIsInZhbHVlIjoiSW1Ra1dEakUrZjRGZzEzcXRRTWkraUc2N3ZsL0F4Ym9QVFgxWTMyYTg1cDRiM0srS0ZvWlBOZCt6Wk0vNW1meTVud0pIaU5YNW1pRFIrYTZGQ3o4Wm4weERteHVJaVBrRmcyS2l3WTVISEsvOUJoaTV0MWxNWkYwOEtMd082bVUiLCJtYWMiOiI3NmVmNDk3MzNiNWNjMzhlOTliMzQxNjFjMjUyOGI1N2U2ZWU2OWQ1ZGJlZWE3NjlmZDRkMTdmMjBmMjI2YWM2In0%3D"
            },
            "body": {
                "email": "[email protected]",
                "username": "exampleusername",
                "first_name": "Exam",
                "last_name": "Ple"
            }
        })
        .then(response => console.log(response))
        .catch(err => console.error(err));

I used corsproxy.io to bypass cors without any fuss