We just fixed two issues with the eraser - 

• Erased lines showed for late joiners
• Lines could get stuck in the 'invisible' state when moving the eraser through them quickly.

You can download the full fixed project here: Sketchbook Jam 1.0.1
If you already have a project, you can import this unitypackage to just update the fixed programs: Sketchbook Jam 1.0.1 Patch

If you're curious about what changed:

Previously, the Eraser triggered an 'Erase' event on a particular Line to everyone in the instance. This event set the line to be Inactive. 

Now, the Eraser triggers an 'Erase' event on the line, just on the Owner of the line. The owner then sets the number of points on the line to be 0, and triggers the 'OnUpdate' event, which has the logic to update line data for everyone. So everyone gets an update that the target line doesn't have any points, which syncs properly for late joiners.

Additionally, each line checks that its renderer is enabled whenever it receives updates, to if it got into a disabled state from an eraser hovering over it, it will fix itself then.