Issue Description:

I'm preventing certain biomes from spawning by setting their ids to -1 in biome_ids.json. One of these is the "dead_forest" biome. My log file shows this error:

[09:20:05] [Server thread/ERROR] [FML]: Parsing error loading built-in advancement biomesoplenty:biomesoplenty/all_biomes
com.google.gson.JsonSyntaxException: Unknown biome 'biomesoplenty:dead_forest'
at net.minecraft.advancements.critereon.LocationPredicate.func_193454_a(SourceFile:77) ~[aq.class:?]
at net.minecraft.advancements.critereon.PositionTrigger.func_192166_a(SourceFile:59) ~[ar.class:?]
at net.minecraft.advancements.critereon.PositionTrigger.func_192166_a(SourceFile:18) ~[ar.class:?]
at net.minecraft.advancements.Criterion.func_192145_a(SourceFile:35) ~[n.class:?]
at net.minecraft.advancements.Criterion.func_192144_b(SourceFile:46) ~[n.class:?]
at net.minecraft.advancements.Advancement$Builder.func_192059_a(SourceFile:204) ~[i$a.class:?]
at net.minecraft.advancements.AdvancementManager$1.deserialize(AdvancementManager.java:50) ~[ns$1.class:?]
at net.minecraft.advancements.AdvancementManager$1.deserialize(AdvancementManager.java:46) ~[ns$1.class:?]
at com.google.gson.internal.bind.TreeTypeAdapter.read(TreeTypeAdapter.java:69) ~[TreeTypeAdapter.class:?]
at net.minecraft.util.JsonUtils.func_188173_a(SourceFile:492) ~[rc.class:?]
at net.minecraft.util.JsonUtils.func_193839_a(SourceFile:532) ~[rc.class:?]
at net.minecraftforge.common.ForgeHooks.lambda$loadAdvancements$0(ForgeHooks.java:1357) ~[ForgeHooks.class:?]
at net.minecraftforge.common.crafting.CraftingHelper.findFiles(CraftingHelper.java:821) [CraftingHelper.class:?]
at net.minecraftforge.common.ForgeHooks.loadAdvancements(ForgeHooks.java:1339) [ForgeHooks.class:?]
at net.minecraftforge.common.ForgeHooks.loadAdvancements(ForgeHooks.java:1313) [ForgeHooks.class:?]
at net.minecraft.advancements.AdvancementManager.func_192779_a(AdvancementManager.java:69) [ns.class:?]
at net.minecraft.advancements.AdvancementManager.(AdvancementManager.java:60) [ns.class:?]
at net.minecraft.world.WorldServer.func_175643_b(WorldServer.java:156) [oo.class:?]
at net.minecraft.server.integrated.IntegratedServer.func_71247_a(IntegratedServer.java:122) [chd.class:?]
at net.minecraft.server.integrated.IntegratedServer.func_71197_b(IntegratedServer.java:156) [chd.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_144]
[09:20:05] [Server thread/INFO] [net.minecraft.advancements.AdvancementList]: Loaded 1067 advancements

Seems to me that the achievement should check if the biomes in it are present or not.

Affected Versions (Exact numbers, do NOT use "latest"):

• Biomes O' Plenty: BiomesOPlenty-1.12.2-7.0.1.2387-universal
• Minecraft: 1.12.2
• Forge: forge-1.12.2-14.23.3.2673-installer-win

We can't. The advancements use json files like vanilla, not code. I'm not sure if Forge added extended support to create advancements with code either.

Bummer, ah well, hope the advancements are not important to the mod's progress.