We use `export default` begrudgingly here. Ideally we'd use just `export`, though this entire SDK expects things to be exported as a default. Instead of breaking everything, we'll sacrifice our export pattern for a smaller diff - a later commit can always do the default export -> regular export conversion.
have seen errors in this direction, so hope this will fix it,
as this is invoked from any EventTile's onHeightChanged callback,
which is often called after some async operation (by when the
timeline can be unmounted already).
doesn't hurt in any case.
instead of setting a min-height on the whole timeline,
track how much height we need to add to prevent shrinking
and set paddingBottom on the container element of the timeline.
as we're approaching from the last node, if we're scrolled up,
the first node we encounter would be below the bottom of the viewport
change the logic to stop at the first node that has its top
above the viewport bottom.
When completely scrolled up, this was causing nodes way below
the viewport to be selected as the reference for the pixelOffset,
and when pagination came in, it would immediately try to apply
the big negative pixelOffset, scrolling to a negative scrollTop,
thus going to the top again, and triggering another pagination,
entering in an infinite pagination loop until you scrolled down.
this is not nearly as smooth as using ResizeObserver, as the
callback rate is a lot lower, but seems to be quite a bit better
than what we have right now, without the 7% cpu hog that
the requestAnimationFrame polling fallback has.
before we would clear it as soon as you were 1px away from
the bottom of the timeline, which would still create jumping as
the whitespace would around 36px. To play it safe, we only clear it
after moving 200px from the bottom.
Also include "local echo" scroll events, caused by setting scrollTop
