[BUG] motionValue sometimes set to NaN via animate utility

[jedierikb]

Sometimes when resetting an animate on a motionValue, the motionValue becomes NaN.

In this codepen, click to reset the target of the animation a few times and the motion value becomes set to NaN.
https://codesandbox.io/s/animate-results-in-nan-um7ec?file=/src/App.tsx

The motion value should never be set to NaN.

[jedierikb]

Here is a video
https://photos.app.goo.gl/NYTusgmh347JnXik8

[jedierikb]

NaN happens when the animate object has the duration parameter and does not seem to happen when duration is omitted.

https://codesandbox.io/s/animate-results-in-nan-forked-0xlq6?file=/src/App.tsx:405-426

[jedierikb]

Poking about in framer-motion source, I see my calls go to popmotion via

motion/src/animation/utils/transitions.ts

Line 198 in e8e7906

: animate({

but grabbing some parameters which cause the bug and feeding them into popmotion directly does not cause onUpdate to go NaN:
https://codesandbox.io/s/animate-results-in-nan-forked-nopfx?file=/src/App.tsx

Not sure off the top of my head the next best path to debug this...

[jedierikb]

Dug into popmotion a bit to trace this.

It seems that sometimes when a derived Velocity is added to a settings object, tween updates return NaN.

Here is a contrived example with a known errant velocity and duration:
https://codesandbox.io/s/animate-results-in-nan-um7ec?file=/src/App.tsx

Here are my rough notes from tracing in popMotion:

in createSpring, if damping == 0 and stiffness == 0, then
dampingRatio is NaN
and then dampedAngularFreq_1 is NaN
and then ResolveSpring returns NaN

Let me know if I should open a ticket in popmotion. Thank you for help in debuggng this.

[mattgperry]

Thanks for the popmotion ticket! I'll close this one so it's just tracked in one place.