errorHandler = function (message, exception) {
                var errorMessage = "Unable to import meshes from " + rootUrl + sceneFilename + (message ? ": " + message : "");
                if (onError) {
                    onError(scene, errorMessage, exception);
                }
                else {
                    BABYLON.Tools.Error(errorMessage);
                    // should the exception be thrown?
                }
                scene._removePendingData(loadingToken);
            }
Import meshes into a scene
@param meshNames an array of mesh names, a single mesh name, or empty string for all meshes that filter what meshes are imported
@param rootUrl a string that defines the root url for scene and resources
@param sceneFilename a string that defines the name of the scene file. can start with "data:" following by the stringified version of the scene
@param scene the instance of BABYLON.Scene to append to
@param onSuccess a callback with a list of imported meshes, particleSystems, and skeletons when import succeeds
@param onProgress a callback with a progress event for each file being loaded
@param onError a callback with the scene, a message, and possibly an exception when import fails