document.timeline.play(
new SequenceEffect([
new GroupEffect([new KeyframeEffect(null, [], 100)]),
new GroupEffect([new KeyframeEffect(null, [], 100)], {fill: 'forwards'}),
])
);
Stack trace:
web-animations-next-animation.js:133 Uncaught TypeError: Cannot read property '_setExternalAnimation' of undefined
at b.Animation._setExternalAnimation (web-animations-next-animation.js:133)
at b.Animation._setExternalAnimation (web-animations-next-animation.js:133)
at Object.b.bindAnimationForGroup (group-constructors.js:199)
at b.Animation._rebuildUnderlyingAnimation (web-animations-next-animation.js:95)
at new b.Animation (web-animations-next-animation.js:39)
at b.AnimationTimeline._play (timeline.js:48)
at b.AnimationTimeline.play (timeline.js:65)
at <anonymous>:1:19
Repro:
Stack trace: