*totally didn't forget*
java.lang.IllegalArgumentException: Slot 4095 is already occupied by net.minecraft.jammy780.furniture.blocks.wood.jfm_WoodBlocksOne@569bfd69 when adding biomesoplenty.blocks.BlockMoss@1b1a24eb
You have conflicting item IDs.
If you remove jammy's furniture, then you can load up the game, go into the NEI options menu, and do an item ID dump. It'll generate a text file in the modpack's folder that you can view, and it should show all the available item IDs. Add in jammys furniture again, go into it's config file and change all the IDs to IDs that aren't being used.
If it still crashes, look in the log to see if an error similar to the one up there shows up. If it does, then the mod might be doing something with it's item IDs automatically or you made a typo and gave it an item ID that was already taken. Also, if you get an outOfBoundsException, then you gave a block an ID that's too high. The item ID limit is around 30 thousand, the block ID limit is around four thousand.