I placed a round, smooth quartz prismarine lantern sideways next to a glass pane. Game instantly crashes, whenever I load the chunk back (the moment I load the world) it crashes again.

"The game crashed whilst tesselating block model
Error: java.lang.ArrayIndexOutOfBoundsException: -271
Exit Code: -1"
crash-2020-09-11_21.13.14-client.txt

Thank you for the report. Unfortunately I'm unable to reproduce this. From the logs it appears a block on or near a chunk boundary is requesting the collision shape for an Exotic Block block and that block is requesting block state for a block outside the render region. The actual block being rendered in the log is a blast furnace.

I've [added additional error handling] (grondag/exotic-matter-2@7642079) to catch this and prevent a crash, but it's unclear what the underlying problem might be. The new check will be available on curseforge soon.