[BUG] Cannot read properties of null (reading 'start')

[galvin96]

1. Read the FAQs 👇

2. Describe the bug

In the motion/packages/framer-motion/src/animation/utils/is-animation-controls.ts file, variable v can be null. So we can't get start of that variable.

3. IMPORTANT: Provide a CodeSandbox reproduction of the bug

https://codesandbox.io/s/dry-sound-hvcyno?file=/src/App.js

4. Steps to reproduce

Steps to reproduce the behavior:

1. Go to CodeSandBox
2. Click on 'Click here'
3. See error

5. Expected behavior

check out the console

[galvin96]

I fixed that problem, could you give me permission to push my commit?

[tomfinney]

had this issue pop up for me the other day. there was some naive typing on my part passing down null instead of undefined and, unless i'm missing something, some naive typing in framer letting you pass in null when null isn't expected and breaks

export function isAnimationControls(v?: unknown): v is AnimationControls {
    return typeof v === "object" && typeof (v as any).start === "function"
}

this check should probably look to exclude null like return typeof v === "object" && v !== null && typeof (v as any).start === "function"? but if null is not meant to be allowed at all, maybe some type def should be modified too?

[a-rbsn]

I've also just encountered this error after updating an older project — the project worked fine before, will update here if I find out why it's happening in my case — I can't find any reference to animation controls in my next js directories.

[galvin96]

I think it's just a simple problem. We can solve it easily if I have permission to push commit and raise a PR.

[a-rbsn]

Yes, I was using a seperate library for detecting whether the element was in the viewport and returning a null to animate= if not, had to replace a {} instead to regain the functionality.