[MC-188542] Custom world gen settings causes minecraft to crash upon import

Upon import the file known as, a_worldgen_settings.txt, minecraft will crash when the settings are imported and doesn't give a chance of world generation. It gives this error in that box, "java.lang.NullPointerException: mouseClicked event handler", and the file used for generation and the crash report for the file are included below.
A seemingly related bug was reported in version 20w21a, but for superflat worlds.
~~MC-184730~~
(1.16 Pre-Release 3) crash-2020-06-10_18.07.33-client.txt
Description: mouseClicked event handler

java.lang.NullPointerException: mouseClicked event handler
	at cfk$c.a(SourceFile:174)
	at cfk$c$$Lambda$3923/1063294170.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at cfk$c.a(SourceFile:174)
	at cfk$c$$Lambda$3922/1208340763.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at cfk$c.a(SourceFile:174)
	at cfk$c$$Lambda$3920/1777689771.accept(Unknown Source)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.accept(ForEachOps.java:184)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.Iterator.forEachRemaining(Iterator.java:116)
	at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:512)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:502)
	at java.util.stream.ForEachOps$ForEachOp.evaluateSequential(ForEachOps.java:151)
	at java.util.stream.ForEachOps$ForEachOp$OfRef.evaluateSequential(ForEachOps.java:174)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.forEach(ReferencePipeline.java:418)
	at cfk$c.decode(SourceFile:170)
	at com.mojang.serialization.MapDecoder.lambda$compressedDecode$0(MapDecoder.java:52)
	at com.mojang.serialization.MapDecoder$$Lambda$3877/1734747662.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.MapDecoder.compressedDecode(MapDecoder.java:52)
	at com.mojang.serialization.MapCodec$MapCodecCodec.decode(MapCodec.java:91)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at com.mojang.serialization.codecs.FieldDecoder.decode(FieldDecoder.java:29)
	at com.mojang.serialization.MapCodec$1.decode(MapCodec.java:34)
	at com.mojang.serialization.codecs.KeyDispatchCodec.lambda$null$1(KeyDispatchCodec.java:57)
	at com.mojang.serialization.codecs.KeyDispatchCodec$$Lambda$3894/606708335.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.codecs.KeyDispatchCodec.lambda$decode$2(KeyDispatchCodec.java:48)
	at com.mojang.serialization.codecs.KeyDispatchCodec$$Lambda$3893/868388621.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.codecs.KeyDispatchCodec.decode(KeyDispatchCodec.java:46)
	at com.mojang.serialization.MapDecoder.lambda$compressedDecode$0(MapDecoder.java:52)
	at com.mojang.serialization.MapDecoder$$Lambda$3877/1734747662.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.MapDecoder.compressedDecode(MapDecoder.java:52)
	at com.mojang.serialization.MapCodec$MapCodecCodec.decode(MapCodec.java:91)
	at com.mojang.serialization.Codec$1.decode(Codec.java:45)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at com.mojang.serialization.codecs.FieldDecoder.decode(FieldDecoder.java:29)
	at com.mojang.serialization.MapCodec$1.decode(MapCodec.java:34)
	at com.mojang.serialization.codecs.RecordCodecBuilder$Instance$7.decode(RecordCodecBuilder.java:409)
	at com.mojang.serialization.codecs.RecordCodecBuilder$Instance$7.decode(RecordCodecBuilder.java:405)
	at com.mojang.serialization.codecs.RecordCodecBuilder$2.decode(RecordCodecBuilder.java:107)
	at com.mojang.serialization.MapDecoder.lambda$compressedDecode$0(MapDecoder.java:52)
	at com.mojang.serialization.MapDecoder$$Lambda$3877/1734747662.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.MapDecoder.compressedDecode(MapDecoder.java:52)
	at com.mojang.serialization.MapCodec$MapCodecCodec.decode(MapCodec.java:91)
	at com.mojang.serialization.codecs.EitherCodec.decode(EitherCodec.java:28)
	at com.mojang.serialization.Decoder$2.decode(Decoder.java:63)
	at com.mojang.serialization.Codec$2.decode(Codec.java:71)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at com.mojang.serialization.codecs.FieldDecoder.decode(FieldDecoder.java:29)
	at com.mojang.serialization.MapCodec$1.decode(MapCodec.java:34)
	at com.mojang.serialization.codecs.RecordCodecBuilder$Instance$5.decode(RecordCodecBuilder.java:325)
	at com.mojang.serialization.codecs.RecordCodecBuilder$2.decode(RecordCodecBuilder.java:107)
	at com.mojang.serialization.codecs.KeyDispatchCodec.lambda$null$1(KeyDispatchCodec.java:57)
	at com.mojang.serialization.codecs.KeyDispatchCodec$$Lambda$3894/606708335.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.codecs.KeyDispatchCodec.lambda$decode$2(KeyDispatchCodec.java:48)
	at com.mojang.serialization.codecs.KeyDispatchCodec$$Lambda$3893/868388621.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.codecs.KeyDispatchCodec.decode(KeyDispatchCodec.java:46)
	at com.mojang.serialization.MapDecoder.lambda$compressedDecode$0(MapDecoder.java:52)
	at com.mojang.serialization.MapDecoder$$Lambda$3877/1734747662.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.MapDecoder.compressedDecode(MapDecoder.java:52)
	at com.mojang.serialization.MapCodec$MapCodecCodec.decode(MapCodec.java:91)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at com.mojang.serialization.codecs.FieldDecoder.decode(FieldDecoder.java:29)
	at com.mojang.serialization.MapCodec$1.decode(MapCodec.java:34)
	at com.mojang.serialization.codecs.RecordCodecBuilder$Instance$3.decode(RecordCodecBuilder.java:249)
	at com.mojang.serialization.codecs.RecordCodecBuilder$2.decode(RecordCodecBuilder.java:107)
	at com.mojang.serialization.MapDecoder.lambda$compressedDecode$0(MapDecoder.java:52)
	at com.mojang.serialization.MapDecoder$$Lambda$3877/1734747662.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.MapDecoder.compressedDecode(MapDecoder.java:52)
	at com.mojang.serialization.MapCodec$MapCodecCodec.decode(MapCodec.java:91)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at com.mojang.serialization.codecs.BaseMapCodec.lambda$decode$2(BaseMapCodec.java:31)
	at com.mojang.serialization.codecs.BaseMapCodec$$Lambda$3883/146690937.apply(Unknown Source)
	at java.util.stream.ReduceOps$1ReducingSink.accept(ReduceOps.java:80)
	at java.util.stream.ReferencePipeline$3$1.accept(ReferencePipeline.java:193)
	at java.util.Iterator.forEachRemaining(Iterator.java:116)
	at java.util.Spliterators$IteratorSpliterator.forEachRemaining(Spliterators.java:1801)
	at java.util.stream.AbstractPipeline.copyInto(AbstractPipeline.java:512)
	at java.util.stream.AbstractPipeline.wrapAndCopyInto(AbstractPipeline.java:502)
	at java.util.stream.ReduceOps$ReduceOp.evaluateSequential(ReduceOps.java:708)
	at java.util.stream.AbstractPipeline.evaluate(AbstractPipeline.java:234)
	at java.util.stream.ReferencePipeline.reduce(ReferencePipeline.java:484)
	at com.mojang.serialization.codecs.BaseMapCodec.decode(BaseMapCodec.java:27)
	at com.mojang.serialization.codecs.UnboundedMapCodec.lambda$decode$0(UnboundedMapCodec.java:38)
	at com.mojang.serialization.codecs.UnboundedMapCodec$$Lambda$3881/2047238003.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.codecs.UnboundedMapCodec.decode(UnboundedMapCodec.java:38)
	at com.mojang.serialization.Decoder$2.decode(Decoder.java:63)
	at com.mojang.serialization.Codec$2.decode(Codec.java:71)
	at uc.decode(SourceFile:34)
	at com.mojang.serialization.Decoder$2.decode(Decoder.java:63)
	at com.mojang.serialization.Codec$2.decode(Codec.java:71)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at com.mojang.serialization.codecs.FieldDecoder.decode(FieldDecoder.java:29)
	at com.mojang.serialization.MapCodec$1.decode(MapCodec.java:34)
	at com.mojang.serialization.codecs.RecordCodecBuilder$Instance$5.decode(RecordCodecBuilder.java:324)
	at com.mojang.serialization.codecs.RecordCodecBuilder$2.decode(RecordCodecBuilder.java:107)
	at com.mojang.serialization.MapDecoder.lambda$compressedDecode$0(MapDecoder.java:52)
	at com.mojang.serialization.MapDecoder$$Lambda$3877/1734747662.apply(Unknown Source)
	at com.mojang.serialization.DataResult.lambda$flatMap$10(DataResult.java:138)
	at com.mojang.serialization.DataResult$$Lambda$517/247924517.apply(Unknown Source)
	at com.mojang.datafixers.util.Either$Left.map(Either.java:38)
	at com.mojang.serialization.DataResult.flatMap(DataResult.java:136)
	at com.mojang.serialization.MapDecoder.compressedDecode(MapDecoder.java:52)
	at com.mojang.serialization.MapCodec$MapCodecCodec.decode(MapCodec.java:91)
	at com.mojang.serialization.Decoder$1.decode(Decoder.java:49)
	at com.mojang.serialization.Codec$2.decode(Codec.java:71)
	at com.mojang.serialization.Decoder.parse(Decoder.java:18)
	at duc.a(SourceFile:206)
	at duc$$Lambda$3184/1910146421.onPress(Unknown Source)
	at dni.b(SourceFile:33)
	at dnc.a(SourceFile:16)
	at dng.a(SourceFile:149)
	at doe.a(SourceFile:27)
	at dly.b(SourceFile:92)
	at dly$$Lambda$2909/1081867337.run(Unknown Source)
	at dqr.a(SourceFile:431)
	at dly.a(SourceFile:92)
	at dly.c(SourceFile:162)
	at dly$$Lambda$2908/859945614.run(Unknown Source)
	at amm.execute(SourceFile:94)
	at dly.b(SourceFile:162)
	at dly$$Lambda$2263/1832606178.invoke(Unknown Source)
	at org.lwjgl.glfw.GLFWMouseButtonCallbackI.callback(GLFWMouseButtonCallbackI.java:36)
	at org.lwjgl.system.JNI.invokeV(Native Method)
	at org.lwjgl.glfw.GLFW.glfwPollEvents(GLFW.java:3101)
	at com.mojang.blaze3d.systems.RenderSystem.flipFrame(SourceFile:109)
	at dgy.e(SourceFile:301)
	at dlx.e(SourceFile:1036)
	at dlx.d(SourceFile:649)
	at net.minecraft.client.main.Main.main(SourceFile:215)