The "Trail Mesh" example code needs modification + I need some clarification

Questions
1

In the documentation for Trail Mesh Trail Mesh | Babylon.js Documentation some example code is provided.

At the beginning, alpha is declared as const alpha = Math.PI;

The scene freezes up when I add this code:

observer = scene.onBeforeRenderObservable.add(animate);
    function animate() {
        alpha += Math.PI/120;
        cube.position.x = Math.sin(alpha) * 10;
        cube.position.y = Math.cos(alpha) * 10;
        cube.rotation.x = (Math.PI * alpha) / 2;
        cube.rotation.y = alpha;
    }

yielding an error in the browser console about assignment to a constant variable. I believe alpha has to be declared as let alpha = ... for the code to work.

Additionally, I do not know why observer can work in this case, even though it has not been declared. If anyone can offer some insight, that would be very helpful.

2

Thanks for reporting, it should be updated soon.

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