Description of the issue:

Game crashes when the voltmeter is equipped/held in the active hand, and the player is looking down to the ground when flying at least 1 entire chunk above ground. Some mouse wiggling may be necessary to reproduce the issue, it does not trigger immediately, but quite reliably after a few seconds.

Reproduced in single player, on a superflat, peaceful, creative world. Put a voltmeter into slot 1 of the toolbar, select it, look down, tap space twice to fly up to around Y35 and wiggle the mouse until the game crashes. Also crashed in non-superflat, but only when flying in my tests, so it is likely that survival worlds are practically not affected. Crashes in IDEA, and normal game start through launcher with Forge 35.1.7, too.

Looks like some shenanigans with unloaded chunk segments being referenced where the NPE is thrown, but I lack intimate knowledge of that code, so apply salt generously. I found that requesting a block update only if the block raytracer hits a FluxReceiver prevented the issue for me. See #4491 for that workaround. Keep in mind I have no idea what I am doing, though, a much better solution may be obvious to you.

--> Crash Log

Versions & Modlist

client-extra.jar |Minecraft |minecraft |1.16.4 |DONE |a1:d4:5e:04:4f:d3:d6:e0:7b:37:97:cf:77:b0:de:ad:4a:47:ce:8c:96:49:5f:0a:cf:8c:ae:b2:6d:4b:8a:3f
forge-1.16.4-35.1.0_mapped_snapshot_20200916-1.16.|Forge |forge |35.1.0 |DONE |NOSIGNATURE
main |Immersive Engineering |immersiveengineering |1.16.4-4.1.1-128 |DONE|NOSIGNATURE