Race condition when removing the map during a pan animation

[arnarp]

How to reproduce

• Leaflet version I'm using: 1.3.1
• Browser (with version) I'm using: Mobile Safari
• OS/Platform (with version) I'm using: iOS 11 & 10
• This is an error reported by my Sentry system. This event has been reported 71 times.
• Open this pen in Safari https://codepen.io/arnarbirgisson/pen/XEYvEE?editors=1010
• It will unmount leaflet after 5 seconds, so pan around until it is removed. When it is removed a type error occurs.

What behaviour I'm expecting and which behaviour I'm seeing

[IvanSanchez]

It's very hard to know what's going on without a reproducible example. Can you try on a controlled environment, seeing if panning the map around makes this error show up on Safari?

[arnarp]

I found a way to reproduce. I updated the issue

• Open this pen in Safari https://codepen.io/arnarbirgisson/pen/XEYvEE?editors=1010
• It will unmount leaflet after 5 seconds, so pan around until it is removed. When it is removed a type error occurs.

[arnarp]

Possible fix is to change map/Map.js

_onPanTransitionEnd: function () {
  DomUtil.removeClass(this._mapPane, 'leaflet-pan-anim');
  this.fire('moveend');
}

to

_onPanTransitionEnd: function () {
  if (this._mapPane !== undefined) {
    DomUtil.removeClass(this._mapPane, 'leaflet-pan-anim');
  }
  this.fire('moveend');
}

because this._mapPane is possible undefined

[IvanSanchez]

@arnarp Could you please try if adding

if (this._panAnim) {
  this._panAnim.stop();
}

to the remove() method of Map would also solve the issue? I feel like it might be a slightly cleaner solution.

[IvanSanchez]

Wait, this should already be happening since #5876 😕