Cannot read property 'then' of undefined

Current behavior

I’m getting a lot of Sentry error reports on 3528:48

    _createClass(SweetAlert, [{
      key: "then",
      value: function then(onFulfilled) {
        var promise = privateProps.promise.get(this); // <-- This line, specifically the 'this'
        return promise.then(onFulfilled);
      }
    }, {
      key: "finally",
      value: function _finally(onFinally) {

I’m trying to reproduce it myself and so far have been unable to do so. It seems this crash can happen as soon as loading the page.

Expected behavior

I would expect the code to handle when promise is undefined. Perhaps there’s a race condition happening here?

Live demo

I’ll just note again I haven’t been able to reproduce it myself, so I would love some advice on what I could do to perhaps test this part of the code and reproduce the issue I’m seeing.

[BoldBigflank]

Yeah I’ll say the solution was to call the function only on views that exist and close this out.

[BoldBigflank]

Got some extra help and found that the issue has something to do with the page’s navigation messing with the weakmap promise implementation.