Cannot assign to read only property 'target' of object '#<AnimationPlaybackEvent>'

[govis]

Description

All Demos yield a Cannot assign to read only property 'target' of object '#<AnimationPlaybackEvent>' error coming from https://github.com/web-animations/web-animations-js/blob/master/src/web-animations-next-animation.js#L223

neon-animation v2.0.0 (2.0-preview)
web-animations-js v2.2.3
polymer v2.0.0-rc.4
webcomponentsjs v1.0.0-rc.8

Expected outcome

No errors

Actual outcome

Cannot assign to read only property 'target' of object '#'" error

Live Demo

Run any of the demos:

Browsers Affected

• Chrome
• Firefox
• Safari 9
• Safari 8
• Safari 7
• Edge
• IE 11
• IE 10

[govis]

Looks like it has something to do with the 2.2.3 commit in web-animations/web-animations-js: web-animations/web-animations-js#123

[krumware]

Getting the same issue over here. neon-animation references web-animations-js version 2.2.0, but version 2.2.3 is the actual version being pulled. 2.2.0 is not an available release tag in web-animations-js https://github.com/web-animations/web-animations-js/releases

[krumware]

Also, I wanted to clarify, the issue here references Polymer 2.0+, but we are seeing the same issue on Polymer 1.8.1

[krumware]

our temporary fix was to add the following to our app's bower.json
"web-animations-js": "web-animations/web-animations-js#2.2.2"

[fungusamongus]

We also had this problem in one of our polymer projects and fixed it by setting the specific 2.2.2 tag in our bower. This is with Polymer 1.8.1

[samuelli]

Just to keep everyone in the loop. I'm trying to get this fixed upstream in web-animations. If that doesn't resolve in the next few hours, we'll go with this stop-gap solution in #230

[krumware]

Thanks Sam!

…

On Apr 13, 2017 5:30 PM, "Sam Li" ***@***.***> wrote: Just to keep everyone in the loop. I'm trying to get this fixed upstream in web-animations. If that doesn't resolve in the next few hours, we'll go with this stop-gap solution in #230 <#230> — You are receiving this because you commented. Reply to this email directly, view it on GitHub <#229 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AQgI5o-xVlY2ugBs-ikl2OPyCVm1CKmPks5rvpPsgaJpZM4M8y8E> .

[samuelli]

Thanks for your patience. This has been fixed upstream in web-animations/web-animations-js#124. Please update to v2.2.4 for web-animations-js and the issue should be resolved.