POSSIBLE BUG: An animation-frame process gets killed while it is in the workQueue thus javascript boom/exception about animation-frame HOT 3 CLOSED

Duplicate of https://github.com/elm-lang/core/issues/628

Thanks for the detailed description though! I ended up figuring it out based on https://github.com/elm-lang/core/issues/628#issuecomment-225719492, which just raised a particular theory. I actually missed his suggestion the first time though because he did not link to the actual lines he was modifying though. Anyway, hopefully that's helpful information.

from animation-frame.

Managed to reduce a program, it happens for me quite reliably in Chrome, just click On then Off a few times and you will eventually see

Main.elm:2417 Uncaught TypeError: Cannot read property 'ctor' of null
step @ Main.elm:2417
work @ Main.elm:2533

pop up into your javascript console fairly quickly and the entire Elm app will stop functioning, thus killing the page. If you attach a debugger in chrome to the javascript and have it stop on unhandled exceptions then you will see exactly where.

The simplified code is (add a dependency on elm-lang/animation-frame as it supplies a wonderfully easy way to reproduce this):

port module Main exposing (..)

import AnimationFrame
import Html
import Html.App
import Html.Events

main =
  Html.App.program
    { init = init
    , view = view
    , update = update
    , subscriptions = subscriptions
    }

init = (0, Cmd.none)

type Msg
  = On
  | Off
  | Tick Float

update msg model =
  case msg of
    On     -> if model == 0 then (1, Cmd.none)       else (model, Cmd.none)
    Off    -> if model >= 1 then (0, Cmd.none)       else (model, Cmd.none)
    Tick t -> if model >= 1 then (model+1, Cmd.none) else (model, Cmd.none)


subscriptions model = if model >= 1 then AnimationFrame.times Tick else Sub.none

view model = Html.div []
  [ Html.text (toString model)
  , Html.button [Html.Events.onClick On]  [Html.text "On"]
  , Html.button [Html.Events.onClick Off] [Html.text "Off"]
  ]

from animation-frame.

This was likely fixed by elm-lang/core@9320969 and should be tested and closed if so.

EDIT: Err, I was beat to it. :-)

from animation-frame.