Shadowing a new field and hotswapping results in a re-transforming error.

[MaslovKK]

[18:17:34] [JDWP Transport Listener: dt_socket/ERROR] (FabricLoader/Mixin/agent) Error while re-transforming target class net/minecraft/client/gui/screen/ingame/HandledScreen
org.spongepowered.asm.mixin.transformer.throwables.MixinTransformerError: An unexpected critical error was encountered
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:392) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClass(MixinTransformer.java:234) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinTransformer.transformClassBytes(MixinTransformer.java:202) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.tools.agent.MixinAgent$Transformer.reApplyMixins(MixinAgent.java:121) [sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.tools.agent.MixinAgent$Transformer.transform(MixinAgent.java:73) [sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at java.instrument/java.lang.instrument.ClassFileTransformer.transform(ClassFileTransformer.java:244) [?:?]
at java.instrument/sun.instrument.TransformerManager.transform(TransformerManager.java:188) [?:?]
at java.instrument/sun.instrument.InstrumentationImpl.transform(InstrumentationImpl.java:610) [?:?]
Caused by: org.spongepowered.asm.mixin.transformer.throwables.MixinPreProcessorException: Attach error for unsorted.mixins.json:HandledScreenMixin from mod unsorted during activity: [Attach field -> widget:Lorg/maslovkk/unsorted/widgets/SortButtonWidget;]
at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.attach(MixinPreProcessorStandard.java:313) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.createContextFor(MixinPreProcessorStandard.java:277) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinInfo.createContextFor(MixinInfo.java:1292) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:203) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.TargetClassContext.apply(TargetClassContext.java:437) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:418) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
... 7 more
Caused by: java.lang.NullPointerException: Cannot invoke "org.spongepowered.asm.mixin.transformer.ClassInfo$Field.remapTo(String)" because "field" is null
at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.attachFields(MixinPreProcessorStandard.java:609) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.attach(MixinPreProcessorStandard.java:302) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinPreProcessorStandard.createContextFor(MixinPreProcessorStandard.java:277) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinInfo.createContextFor(MixinInfo.java:1292) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinApplicatorStandard.apply(MixinApplicatorStandard.java:203) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.TargetClassContext.apply(TargetClassContext.java:437) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.TargetClassContext.applyMixins(TargetClassContext.java:418) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
at org.spongepowered.asm.mixin.transformer.MixinProcessor.applyMixins(MixinProcessor.java:363) ~[sponge-mixin-0.15.4+mixin.0.8.7.jar:0.15.4+mixin.0.8.7]
... 7 more

Using Jetbrains Runtime 21