[Forge 1.20.1] Game crashes when breaking slabs stacked in blocks

[Kouchi0Seu]

Expected Behavior

When breaking a combined slab block with the Shift key pressed, only one slab should break, without causing the game to crash.

Actual Behavior

When breaking a combined slab block with the Shift key pressed, the game crashes.

Steps to Reproduce the Problem

1. Download and install the DoubleSlabs mod
2. Combine multiple slabs into a single block
3. Hold the Shift key and break the combined slab block

Crash report link: https://mclo.gs/O5agdxc

[Kouchi0Seu]

P.S. Also, worth mentioning that reproducing the issue seems a bit inconsistent. Sometimes it crashes immediately and sometimes it takes multiple attempts to actually cause the game to crash.
Maybe it has something to do with breaking slabs fast enough, but I'm not really sure.

[CJMinecraft01]

Thanks for reporting this! What kind of slab did you break? Was it one from another mod?

[Kouchi0Seu]

Just for the sake of testing I've created a separated modpack with only Double Slabs installed to eliminate the possibility of conflicts with other mods. When testing I just place some slabs of the same type (e.g. planks + planks) and some of 2 different types (e.g. planks + bricks). After that I just press Shift key to break half of that block and game crashes. At first, I thought it was only happening with different types of slabs, but after some further testing it appeared that it happens even with the same ones.

I've done a few more tests and it seems that the issue is only present while in creative mode. When in survival there are some other problems with slabs missing textures and stuff like that, but I'm not sure if I should post it all here or create a new issue branch.

Like I said earlier, it's a bit inconsistent to reproduce the issue, but unfortunately I can't find any specific pattern.
The error in the crash report is exactly the same so I don't think there's a need to attach new logs.