ModalBox doesn't work

ModalBox doesn't work

Hi, ModalBox call initialization stopped working. 
I use next code:
  1. App.instance.modal({
    url: '/app/modal.html',
    title: "Modal box"
    }).then(function(modalInfo) {
    const modalInstance = App.instance.getWidgetInstance(modalInfo.widgetID);

    modalInstance.on('modal.opened', function(data) {
    console.log('modal opened ++++++++++++++++++')
    });
    }).catch(function(err) {
    console.log(err, "Modal error");
    })
We have two instances, for production and for developing.
The code of widget is  the same for those instances.
But for developing instance throws an error inside catch block in code above:  widgetMeta is not defined

In production instance this code works correct without any errors.

I would be grateful for the help.