ConcurrentModificationException on editor update of dynamic language that is currently built

[AZWN]

Summary

When rebuilding a language, and triggering an editor update at the same time, a ConcurrentModificationException exception is thrown.

What you did

1. Import some language in Spoofax
2. Create a file in that language
3. Make some changes to the language definition
4. Rebuild the language
5. While the rebuild in in progress, change the object language file

What you expected to happen

The editor update job should wait until the language is rebuilt (or perhaps use the old language definition)

What actually happened

A ConcurrentModificationException exception is thrown

Context

• Spoofax version: 0.19.6
• Operating system & version: MacOs
• Java version (if applicable): Java 11

Additional information

Stacktrace:

java.util.ConcurrentModificationException
	at java.base/java.util.HashMap$HashIterator.nextNode(HashMap.java:1511)
	at java.base/java.util.HashMap$EntryIterator.next(HashMap.java:1544)
	at java.base/java.util.HashMap$EntryIterator.next(HashMap.java:1542)
	at org.nustaq.serialization.serializers.FSTMapSerializer.writeObject(FSTMapSerializer.java:44)
	at org.nustaq.serialization.FSTObjectOutput.writeObjectWithContext(FSTObjectOutput.java:476)
	at org.nustaq.serialization.FSTObjectOutput.writeObjectWithContext(FSTObjectOutput.java:369)
	at org.nustaq.serialization.FSTObjectOutput.writeObjectFields(FSTObjectOutput.java:664)
	at org.nustaq.serialization.FSTObjectOutput.defaultWriteObject(FSTObjectOutput.java:546)
	at org.nustaq.serialization.FSTObjectOutput.writeObjectWithContext(FSTObjectOutput.java:458)
	at org.nustaq.serialization.FSTObjectOutput.writeObjectInternal(FSTObjectOutput.java:327)
	at org.nustaq.serialization.FSTObjectOutput.writeObject(FSTObjectOutput.java:294)
	at mb.pie.serde.fst.FstSerde.serialize(FstSerde.java:35)
	at mb.pie.runtime.store.SerializingStore.serialize(SerializingStore.java:86)
	at mb.pie.runtime.store.SerializingStore.close(SerializingStore.java:80)
	at mb.pie.runtime.PieImpl.close(PieImpl.java:79)
	at mb.pie.dagger.PieComponent.close(PieComponent.java:49)
	at mb.spoofax.core.component.ComponentImpl.close(ComponentImpl.java:59)
	at mb.spoofax.lwb.dynamicloading.component.DynamicComponent.close(DynamicComponent.java:67)
	at mb.spoofax.lwb.dynamicloading.component.DynamicComponentManagerImpl.loadOrReloadFromCompiledSources(DynamicComponentManagerImpl.java:271)
	at mb.spoofax.lwb.dynamicloading.DynamicLoad.run(DynamicLoad.java:116)
	at mb.spoofax.lwb.dynamicloading.DynamicLoad.lambda$exec$0(DynamicLoad.java:93)
	at mb.common.option.Option.mapOrElse(Option.java:146)
	at mb.common.result.Result.flatMap(Result.java:417)
	at mb.spoofax.lwb.dynamicloading.DynamicLoad.exec(DynamicLoad.java:93)
	at mb.spoofax.lwb.dynamicloading.DynamicLoad.exec(DynamicLoad.java:28)
	at mb.pie.api.Task.exec(Task.java:56)
	at mb.pie.runtime.exec.TaskExecutor.execInternal(TaskExecutor.java:130)
	at mb.pie.runtime.exec.TaskExecutor.exec(TaskExecutor.java:87)
	at mb.pie.runtime.exec.BottomUpRunner.exec(BottomUpRunner.java:419)
	at mb.pie.runtime.exec.BottomUpRunner.execAndSchedule(BottomUpRunner.java:132)
	at mb.pie.runtime.exec.BottomUpRunner.execScheduled(BottomUpRunner.java:119)
	at mb.pie.runtime.exec.BottomUpRunner.requireInitial(BottomUpRunner.java:82)
	at mb.pie.runtime.MixedSessionImpl.lambda$updateAffectedBy$0(MixedSessionImpl.java:72)
	at mb.pie.runtime.SessionImpl.handleException(SessionImpl.java:233)
	at mb.pie.runtime.MixedSessionImpl.updateAffectedBy(MixedSessionImpl.java:72)
	at mb.spoofax.lwb.eclipse.SpoofaxLwbBuilder.bottomUpBuild(SpoofaxLwbBuilder.java:132)
	at mb.spoofax.lwb.eclipse.SpoofaxLwbBuilderBase.incrBuild(SpoofaxLwbBuilderBase.java:88)
	at mb.spoofax.lwb.eclipse.SpoofaxLwbBuilderBase$1.run(SpoofaxLwbBuilderBase.java:59)
	at org.eclipse.core.internal.resources.Workspace.run(Workspace.java:2292)
	at mb.spoofax.lwb.eclipse.SpoofaxLwbBuilderBase.build(SpoofaxLwbBuilderBase.java:68)
	at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:846)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:229)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:277)
	at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:330)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:333)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:385)
	at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:406)
	at org.eclipse.core.internal.resources.Workspace.buildInternal(Workspace.java:515)
	at org.eclipse.core.internal.resources.Workspace.build(Workspace.java:405)
	at org.eclipse.ui.actions.GlobalBuildAction$1.run(GlobalBuildAction.java:180)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)