$http.error() returns data as string

Here's the code for the entire $http implementation:

    $http({
        url: jsurl('profile.login'),
        method: 'POST',
        data: $.param({
            username: $scope.username,
            password: $scope.password,
            csrfmiddlewaretoken: $.cookie('csrftoken')
        }),
        headers: {'Content-Type': 'application/x-www-form-urlencoded'}
    }).
    success(function (data) {
        $scope.success = true;
    }).
    error(function (data) {
        $scope.success = false;
        $scope.errors = data.errors;
    });

The issue is that data in $http.error is a string despite returning the following response:

Content-Type:application/json; charset=UTF-8
Body: {"errors":{"username":{"messages":[["Pleaseenteryourusername."]]},"password":{"messages":[["Pleaseenterpassword."]]}},"success":false}

In jQuery I would normally use $.parseJSON() however I keep hearing about how I shouldn't use jQuery code within Angular code (I've yet to understand why this is) so I'm wondering if there's a more Angular canonical method to parsing error response to JSON.