Time slider doesn't go to beginning/end

[davidbrochart]

Description

In a fresh environment, with pip install jupyterlab jupyter-collaboration:

jupyter-collaboration     3.1.0
jupyterlab                4.3.3

We cannot go back to the initial state of the notebook, and then we cannot go back to the latest state.

@Meriem-BenIsmail do you mind having a look at it?

Reproduce

See:

Peek.2024-12-17.15-38.mp4

Expected behavior

[Meriem-BenIsmail]

This seems to be an issue for notebooks only because the slider works as expected for other document types. Is there something that was added for ynotebooks specifically that could be causing this issue by any chance ?