Cannot read property 'then' of undefined

CheckList.prototype.addClickHandler = function(fn) {
this.$element.on(‘click’, ‘input’, function(event) {
var email =;

  .then(function () {

Uncaught TypeError: Cannot read property ‘then’ of undefined
at CheckList. (checklist.js:32)
at HTMLDivElement.dispatch (jquery.js:4435)
at HTMLDivElement.elemData.handle (jquery.js:4121)

backed out the then which id like to resolve.
still having an issue removing the row from the page.

I suspect this is actually because I receive a validation error in my server response creating the row.

I would like to finish this chapter clean before moving on. Loving the books even though I feel like I am starting to wrestle with it a bit.

Resolved my validation error by resolving issues building my data. i set an attribute called email. the server wants emailaddress. i am unsure if I am just confused about what is the value or the label (email:emailAddress) . I think the book transposes them at arbitrary times.

apparently the root of my issue was addRow not AddRow. Resolved and working well.