Whenever I try creating, loading or importing (be it manually or through Multiverse) a Void World (a world that only procedurally generates air blocks), the server stalls and crashes with a bunch of the following errors:

[15:33:20] [Worker-Main-30/FATAL]: Failed to schedule load callback for chunk [-11, -1]
java.util.concurrent.CompletionException: net.minecraft.server.v1_16_R1.ReportedException: Exception generating new chunk
{{ at java.util.concurrent.CompletableFuture.encodeThrowable(Unknown Source) ~[?:1.8.0_241]}}
{{ at java.util.concurrent.CompletableFuture.completeThrowable(Unknown Source) ~[?:1.8.0_241]}}
{{ at java.util.concurrent.CompletableFuture.uniCompose(Unknown Source) ~[?:1.8.0_241]}}
{{ at java.util.concurrent.CompletableFuture$UniCompose.tryFire(Unknown Source) ~[?:1.8.0_241]}}
{{ at java.util.concurrent.CompletableFuture$Completion.run(Unknown Source) ~[?:1.8.0_241]}}
{{ at net.minecraft.server.v1_16_R1.ChunkTaskQueueSorter.b(SourceFile:58) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ThreadedMailbox.e(SourceFile:94) [spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ThreadedMailbox.a(SourceFile:137) [spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ThreadedMailbox.run(SourceFile:105) [spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at java.util.concurrent.ForkJoinTask$RunnableExecuteAction.exec(Unknown Source) [?:1.8.0_241]}}
{{ at java.util.concurrent.ForkJoinTask.doExec(Unknown Source) [?:1.8.0_241]}}
{{ at java.util.concurrent.ForkJoinPool$WorkQueue.runTask(Unknown Source) [?:1.8.0_241]}}
{{ at java.util.concurrent.ForkJoinPool.runWorker(Unknown Source) [?:1.8.0_241]}}
{{ at java.util.concurrent.ForkJoinWorkerThread.run(Unknown Source) [?:1.8.0_241]}}
Caused by: net.minecraft.server.v1_16_R1.ReportedException: Exception generating new chunk
{{ at net.minecraft.server.v1_16_R1.PlayerChunkMap.lambda$26(PlayerChunkMap.java:551) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.PlayerChunkMap.lambda$24(PlayerChunkMap.java:536) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ ... 12 more}}
Caused by: java.lang.UnsupportedOperationException
{{ at com.google.common.collect.ImmutableMap.clear(ImmutableMap.java:620) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ChunkGenerator.updateStructureSettings(ChunkGenerator.java:309) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ChunkGenerator.a(ChunkGenerator.java:233) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ChunkGenerator.createStructures(ChunkGenerator.java:212) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ChunkStatus.d(SourceFile:51) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.ChunkStatus.a(SourceFile:219) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.PlayerChunkMap.lambda$26(PlayerChunkMap.java:538) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at com.mojang.datafixers.util.Either$Left.map(Either.java:38) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ at net.minecraft.server.v1_16_R1.PlayerChunkMap.lambda$24(PlayerChunkMap.java:536) ~[spigot-1.16.1.jar:git-Spigot-758abbe-2b00831]}}
{{ ... 12 more}}