[21:37:35 ERROR]: Encountered an unexpected exception
java.lang.IllegalArgumentException: Cannot get ID of Modern Material
at org.apache.commons.lang.Validate.isTrue(Validate.java:136) ~[patched_1.15.2.jar:git-Paper-161]
at org.bukkit.Material.getId(Material.java:3334) ~[patched_1.15.2.jar:git-Paper-161]
at com.biel.FastSurvival.OverworldStructures.NetherPopulator.populate(NetherPopulator.java:50) ~[?:?]
at net.minecraft.server.v1_15_R1.Chunk.loadCallback(Chunk.java:680) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.PlayerChunk.lambda$null$11(PlayerChunk.java:530) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.PlayerChunkMap$CallbackExecutor.run(PlayerChunkMap.java:103) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.ChunkProviderServer$a.executeNext(ChunkProviderServer.java:908) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.ChunkProviderServer.runTasks(ChunkProviderServer.java:506) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.MinecraftServer.ba(MinecraftServer.java:1047) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.MinecraftServer.executeNext(MinecraftServer.java:1031) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.IAsyncTaskHandler.awaitTasks(IAsyncTaskHandler.java:119) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.MinecraftServer.sleepForTick(MinecraftServer.java:1015) ~[patched_1.15.2.jar:git-Paper-161]
at net.minecraft.server.v1_15_R1.MinecraftServer.run(MinecraftServer.java:938) ~[patched_1.15.2.jar:git-Paper-161]
at java.lang.Thread.run(Thread.java:748) [?:1.8.0_242]