Version of Advanced Rocketry
1.12.2-2.0.0-13

Have you verified this is an issue in the latest unstable build
Yes

Version of LibVulpes
1.12.2-0.4.2-75

Version of Minecraft
1.12.2

Does this occur without other mods installed
Not tested, probably not

Crash report or log
https://pastebin.com/q5LtauQt

Description of the problem
Crash on game initialization related to "et.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Advanced Rocketry (advancedrocketry)
Caused by: java.lang.NoClassDefFoundError: zmaster587/advancedRocketry/tile/infrastructure/TileRocketMonitoringStation"

Updating both (LibVulpes to 1.12.2-0.4.2-25 and JAOPCA to 1.12.2-2.2.8.106) fixed indicated problem. Issue resolved.