Better Slabs crashing server of start for 1.12.2

When using this mod on any version of 1.12.2 forge or any version of the better slabs mod, my server crashes when starting. The solutions given to fix this problem don't seem to help. https://mclo.gs/gWJ3Hff

The mod works for me just on a single player world, and for my friends as well, but the server is having some error with it.