Lottie Animator

Lottie is JSON, which makes it easy to write and easy to write wrongly. The failure mode is specific and nasty: a broken Lottie still parses. A missing os on a polystar, an easing handle one level too high, a layer without ip/op — the file loads, the player reports no error, and the canvas stays empty.

So do not judge an animation by whether the JSON is valid. Judge it by looking at it.

The loop

convert  →  lint  →  render  →  LOOK  →  revise

Never skip the render. "The JSON is valid" is not a claim about what the user sees.