Bit of redstone that worked in pre-2, crashes in pre-3.  A dispenser is placing a shulker with items on top of a hopper, the dispenser is powered by an adjacent target block.

Game crashes when dispenser places.

May or may not have something to do with the piston that is extended over the hopper, set to retract based of a redstone torch on the same target block.  Found it weird that worked up to now.

Crash reports attached.  Contraption in question can be seen in this video at the 38s mark.
https://www.youtube.com/watch?v=XCFx4PjvLgA