Ajax request always failing

[Declan Murphy]

I am trying to create a script that hides a field if an issue is in a particular status. To get the status, I am making an ajax request to the Rest API. However, this request keeps failing and I'm not sure why.
The ajax request is as follows:

function getStatus() {
        var issueKey = JIRA.Issue.getIssueKey();
        var restUrl = "/rest/api/2/issue/" + issueKey;
        var statusname;
        console.log('KEY : ' + issueKey);
        console.log('URL : ' + restUrl);
        
        AJS.$.ajax({
            url: restUrl,
            type: 'get',
            dataType: 'json',
            contentType: "application/json",
        })
		.done(function(data) {
            statusname = data.fields.status.name;
            console.log('Status Name : ' + statusname);
            return statusname;
        })
        .fail(function() {
            console.log('ERROR');
        })
        .always(function(data) {
            console.log('DATA : ' + data);
        });
 }

Could someone tell me why this is failing and where I've gone wrong? Alternatively, is there an easier/short-hand way to get the status of an issue?

[Volodymyr Krupach]

What HTTP status does it return? Is there respsonse body?