findExistingRecord( modelName, id, options ) {
		options = assign( { reload: true }, options );

		return this.findRecord( modelName, id, options )
			.catch( err => {
				// unload the generated empty record
				const record = this.peekRecord( modelName, id );

				if ( record ) {
					this.unloadRecord( record );
				}

				return Promise.reject( err );
			});
	}
Find a record and unload the generated record
@param {string} modelName
@param {string|number} id
@param {Object?} options
@param {boolean?} options.reload
@returns {Promise.<Model>}