[BUG] Animations are cancelled after one tick

[Jameskmonger]

Describe the bug
Animations are cancelled after one tick of playing, they should continue to play to the end.

To Reproduce
Steps to reproduce the behavior:

1. Run an emote such as "Jump for joy", you will notice it doesn't complete
2. If you spam-click the animation button, the emote will complete

Expected behavior
The emote should run to its finish.

Additional context

I was able to fix this locally by going into player-sync-task.ts and changing the updateFlags.animation !== undefined checks to updateFlags.animation !== undefined && updateFlags.animation !== null.

The issue is that the "Reset animation" part is being called every tick, thus setting the animation back to -1.

Possibly we can just remove the undefined check entirely, and only check against null.