Verification builds:

1.2.10 Beta

Summary:

Certain interactions where a piston pushes another piston (directly or indirectly) result in a crash. They mostly seem to involve observers powering the pistons to trigger said crash. Sticky and normal pistons both result in crashes.

Steps to Reproduce:

Sample A - Replace the quartz block with an observer such that it powers the adjacent piston.
Sample B - Remove one or both of the obsidian blocks holding down the flying machine, then update one of the far end observers on the left or right.
Sample C - Update the observer on the left.
Sample D - Update the observer on the right.

Observed Results:

The observer updates the piston, which begins to extend, then the game crashes.

Expected Results:

The piston extends as normal, pushing any other piston/observer, piston/slimeblock, and piston/piston combinations as normal.

Screenshots/Videos attached:

Yes

Notes:

I noticed that this seems to trigger a crash only when the first piston is initially powered by a short pulse (i.e. observer). Needs more testing.