lib/relations/belongs_to.js
function(instance) {
    var result = this._related(instance);
    if (result === undefined) {
      throw new Error(util.format('The relation "%s" has not yet been ' +
        'loaded.', this._name));
    }
    return result;
  }
function(instance) {
    var result = this._related(instance);
    if (result === undefined) {
      throw new Error(util.format('The relation "%s" has not yet been ' +
        'loaded.', this._name));
    }
    return result;
  }
function ( instance ) { var result = this . _related ( instance ) ; if ( result === undefined ) { throw new Error ( util . format ( 'The relation "%s" has not yet been ' + 'loaded.' , this . _name ) ) ; } return result ; }
The item property for this relation.

This property allows access to the cached object that has been fetched
for a specific model in a given relation. Before the cache has been
filled, accessing this property will throw an exception.

It is accessible on an individual model via `<singular>` and via
`get<Singular>`. For instance, an article that belongs to an author would
cause this method to get triggered via `article.author` or
`article.getAuthor`.

The naming conventions are set forth in {@link BelongsTo#overrides}.

@method
@protected
@param {Model} instance The model instance on which to operate.
@see {@link BaseRelation#methods}
The item property for this relation .