[11:38:41] [Client thread/ERROR] [FML]: Caught exception from Mekanism
java.lang.NoClassDefFoundError: codechicken/multipart/BlockMultipart

Merp.

[Not really caused by us]

Easy to fix: either add Forge Multipart dev jar to eclipse/mods or add to build.gradle and compile with it. Let me know what you want me to do