Unable to enter world with any version of Cardboard on 1.21.1? NullPointerException on getServer().scoreboardManager

[floral-qua-floral]

I haven't been able to successfully launch the game and load a world with Cardboard for 1.21.1 no matter which combination of Cardboard & ICommonLib I use. I've tested all the possible version combinations of the two with no other mods loaded, but did not have any success. Combinations with API 99 were not possible to test due to iCommonLib#17.

Versions:

• Minecraft 1.21.1
• Fabric Loader 0.17.2
• Fabric API 0.116.6+1.21.1

LOGS	API 99	API 96	API 91
CB 9	Untestable	Log/Crash	Log
CB 3	Untestable	Log	Log
CB 2	Untestable	Log	Log
CB 1	Untestable	Log	Log

All testable combinations crash due to a NullPointerException immediately upon trying to load a world, caused by trying to read the scoreboardManager field of getServer(). It seems like a second NPE also always occurs afterwards while the server is stopping, although the second exception is harder to make sense of because the names in it are obfuscated.

I also tested Cardboard 9 with API 96 and Fabric Loader 0.16.14, as 0.16.14 looks to have been the most recent Fabric Loader version at the time Cardboard 9 was released, however this did not appear to make any difference (log). This test still used Fabric API 0.116.6+1.21.1 as that appears to have been the most recent version at that time as well.

The reason I felt it made sense to test (& include logs for) old versions instead of only the most up-to-date builds is because if my results are universal, then that would indicate that Cardboard has never been useable on 1.21.1. However this seems like it must certainly be false, which makes this issue very confusing to me. I've only tested singleplayer, and all but 1 of my tests used Fabric Loader 0.17.2 and Fabric API 0.116.6 - could either of these be the cause? Is there some issue with the builds uploaded to Modrinth, or with their labeling? This does not look like it would be a hardware-dependent issue, but could it be anyways?

[floral-qua-floral]

Tested using a dedicated server and found that it worked fine (Cardboard 9 and API 96; API 99 still fails on dedicated server). In hindsight, I probably should've checked that first, since my understanding is that Bukkit/Spigot/Paper do normally only work on dedicated server anyways; I just figured that Cardboard would function the same on the integrated server as it does on a dedicated one, like most server-sided Fabric mods. My mistake! If this is an intended limitation, it might be worth adding a note about it on the Modrinth page, and perhaps also notifying the player in-game on the title screen.