I can't patch a salesforce object using angular and REST api

Question

I'm trying to patch a salesforce object using angular, but am getting no where. Every time I get a nondescript error.

salesforce.patch = function(resource, contentType, data) {
  var http = angular.injector(['ng']).get('$http');
  var defered = angular.injector(['ng']).get('$q').defer();
  var log = angular.injector(['ng']).get('$log');

  var upload = function() {
    log.info('Salesforce - Posting resource \'' + resource + '\'.');

    var url = salesforce.proxy.url + resource;
    http({
      method: 'PATCH',
      url: url,
      headers: {
        'Authorization': salesforce.user.accessTokenType + ' ' + salesforce.user.accessToken,
        'Content-Type': contentType,
        'Target-URL': salesforce.user.url
      },
      data: data
    }).success(function(data) {
      defered.resolve(data);
    }).error(function(error) {
      log.error('Salesforce - Failed to post resource \'' + resource + '\'.');
      salesforce.logApiError(log, error);
      defered.reject();
    });
  };

  salesforce.authenticate().then(upload).catch(defered.reject);

  return defered.promise;
};