Promise

Use formBuilder the moment the instance is available.

Async/Await Usage - (requires transpilation)

async loadFormBuilder() => {
    var formBuilder = await $(fbEditor).formBuilder().promise;
    console.log(formBuilder.formData);
}

Promise.then() Usage

$(fbEditor).formBuilder().promise.then(formBuilder => {
    console.log(formBuilder.formData);
});

See it in Action