Crash on startup when using mod built with Loom 1.15 or higher #266

Minecraft version

1.21.1

Describe the bug

My mod is able to run without issue if built with Loom 1.14. However, updating to Loom 1.15 without changing any mod code causes the game to crash during startup.

Steps to reproduce

I'm not sure if this is in some way specific to my mod or a more general pattern, so the steps to reproduce are just based on my own mod. The mod works fine in a genuine Fabric environment regardless of what version of Loom is used to build it, so this is definitely related to Sinytra in some way.

Mod versions:

• Neoforge 21.1.220 (also tested on 21.1.228)
• Sinytra Connector 2.0.0 beta 14
• Forgified Fabric API 0.116.7+2.2.4
• Cloth Config (Neoforge) 15.0.140 (dependency for marioQuaMario)
• Custom Player Models (Neoforge) 0.6.25a (dependency for marioQuaMario)
• marioQuaMario has not yet been released and as such doesn't have discrete versions. I've been using builds based on commit c91f717.

1. Build marioQuaMario using Loom 1.14. I have a branch on a stable version configured to this version of Loom here.
2. Launch the game with Neoforge, Connector, FFA, marioQuaMario, and its dependencies. The game should reach the title screen without issue.
3. Close the game and build marioQuaMario again using Loom 1.15. I have another branch for that here, which is identical to the Loom 1.14 branch except for the version of Loom.
4. Launch the game using all the previously listed mods at the same versions, but with the new build of marioQuaMario. The game will crash before reaching the title screen.

The crash report lists the content module's ChangeDroppedCoinModel mixin as the failing mixin. I've tried disabling this specific mixin and trying again, but that just causes it to blame a different one from the mod module instead.

Logs

Loom 1.14: https://gist.github.com/floral-qua-floral/2c8e9cdc971f117b31e8b4ad0977732e
Loom 1.15: https://gist.github.com/floral-qua-floral/d54e9704b0e6ec559376efa90ba8daf6

Additional context

The only two mixins I've seen named in the report as the cause of the crash were both WrapOperations, so this issue may be related to that type of mixin specifically?