Loader throws FileSystemAlreadyExistsException with minecraft 1.12

[DeadlyMC]

When trying to run fabric with 1.12 the game loads up until the loading screen but when i open a world it just freezes and i can see an exception in the console. In case of the server it just instantly crashes. I'm running fabric-loader 0.6.1+build.165 This is the crash-report (it generates this for both client and server) : https://pastebin.com/w6ztVvsC

I tried downgrading to a older version. Tested with 0.4.0+build.112 and it worked there. Seems like fabric-loader isn't cleaning up its file system usage properly

[liach]

@sfPlayer1 Does fabric loader treat Minecraft jar as a mod since your minecraft builtin mod change? If yes, I see that some FileSystems on mods are not closed after usage, which may have contributed to this issues.

[Player3324]

Yes, the builtin mods are being associated with the game jar. We already fixed a bug around the resources module not ignoring builtin mods, there may be more cases needing similar fixing.

[liach]

I have successfully reproduced a similar crash of 18w43b (the oldest snapshot supported by Fabric) with a clean installation of loader 0.6.2+build.166. https://gist.github.com/6ef5018540b366949fef7018f1331fe9 The error emerges from resource pack container trying to determine the initial insertion position of the pack.

Meanwhile, a clean installation of loader 0.4.9+build.161 can totally launch fine.

[creeper123123321]

~~Couldn't reproduce on 0.10.8~~ Nevermind, it launched but I didn't open the world. I tested now and could still reproduce

[liach]

Hmm, I think in 1.12 advancements or something alike creates a file system for the jar and expect none to exist beforehand. May that be the cause?

[modmuss50]

It seems this may have been fixed, if not please open a new issue.