The deployer has produced other crashes as well (when placing a sapling in a block that already has one, for example, but doesn't happen always). But this one though seems to crash everytime. I have a very small modlist, provided below

How to reproduce:
Place deployer and give it flint and steel. Rotate it with a mechanical bearing, when it reaches a tile that is already on fire the game crashes. Ingame screenshot for clarity:

Here's the log
latest.log

Love the mod, hoping this helps improve it. Thanks!

Edit: Just tested again. The mechanical bearing isn't necessary, just by making the deployer apply flint & steel on the same block will crash the game.

Hi, Deployers no longer work properly on long outdated forge versions such as any 1.16.3 as well as early 1.16.4 builds.
I suggest updating to 1.16.4 or .5 to fix these incompatibilities

I updated my installation and now it does not happen anymore. I think this can be closed.

I'm very sorry, I didn't notice my Minecraft instalation was old. I'm using curseforge, so I must have missclicked or something because I created the mod pack last week.