App randomly crashing in Dict: Cannot read property 'ctor' of undefined

[seanhess]

My app has historically worked without issues. I'm having some strange issues where it doesn't work as expected when I deliver it to my client. Right now, it crashes with the following message:

Uncaught TypeError: Cannot read property 'ctor' of undefined

On this part of the generated .js

 var get = F2(function (targetKey,dict) {
    get: while (true) {
       var _p4 = dict;
       if (_p4.ctor === "RBEmpty_elm_builtin") {
             return $Maybe.Nothing;
          } else {

The strange thing is every 5 or so hard reloads it works. Like it's a race condition or something? All of this code works perfectly locally, so it's frustrating to debug.

[seanhess]

I found the offending code. It was executed rarely because of a network race condition.

  let res = case model.form of
              Nothing -> res
              Just form -> Session.applyDefaults form model.session.userInfo responses

res is defined recursively, which is an accident. I meant for it to be this:

              Nothing -> model.responses

Should the compiler have caught this for me? Is there some flag I can enable to catch these? Or is it a bug, and if so where should I log it?

Thanks!

[seanhess]

I found the offending code. It was executed rarely because of a network race condition.

  let res = case model.form of
              Nothing -> res
              Just form -> Session.applyDefaults form model.session.userInfo responses

res is defined recursively, which is an accident. I meant for it to be this:

              Nothing -> model.responses

Should the compiler have caught this for me? Is there some flag I can enable to catch these? Or is it a bug, and if so where should I log it?

Thanks!

[jvoigtlaender]

See elm/compiler#873 and a subset of the ton of related issues linked to from there.

[jvoigtlaender]

See elm/compiler#873 and a subset of the ton of related issues linked to from there.

[seanhess]

Thank you!

[seanhess]

Thank you!