An error was encountered while remapping

[supersaiyansubtlety]

On QuiltMC/quilt-mappings@7465c89
When naming any of the params of net/minecraft/unmapped/C_qsrmwluu::m_txjyyfzm
(net/minecraft/network/codec/PacketCodec::tuple of 7)

This soft crash occurs:

java.util.concurrent.CompletionException: java.util.ConcurrentModificationException
	at java.base/java.util.concurrent.CompletableFuture.encodeThrowable(CompletableFuture.java:315)
	at java.base/java.util.concurrent.CompletableFuture.completeThrowable(CompletableFuture.java:320)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:649)
	at java.base/java.util.concurrent.CompletableFuture$Completion.exec(CompletableFuture.java:483)
	at java.base/java.util.concurrent.ForkJoinTask.doExec(ForkJoinTask.java:387)
	at java.base/java.util.concurrent.ForkJoinPool$WorkQueue.topLevelExec(ForkJoinPool.java:1312)
	at java.base/java.util.concurrent.ForkJoinPool.scan(ForkJoinPool.java:1843)
	at java.base/java.util.concurrent.ForkJoinPool.runWorker(ForkJoinPool.java:1808)
	at java.base/java.util.concurrent.ForkJoinWorkerThread.run(ForkJoinWorkerThread.java:188)
Caused by: java.util.ConcurrentModificationException
	at java.base/java.util.HashMap$HashIterator.nextNode(HashMap.java:1605)
	at java.base/java.util.HashMap$EntryIterator.next(HashMap.java:1638)
	at java.base/java.util.HashMap$EntryIterator.next(HashMap.java:1636)
	at com.google.common.collect.AbstractMapBasedMultimap$AsMap$AsMapIterator.next(AbstractMapBasedMultimap.java:1479)
	at com.google.common.collect.AbstractMapBasedMultimap$AsMap$AsMapIterator.next(AbstractMapBasedMultimap.java:1468)
	at org.quiltmc.enigma.api.source.SourceIndex.remapTo(SourceIndex.java:161)
	at org.quiltmc.enigma.api.source.DecompiledClassSource.remapSource(DecompiledClassSource.java:49)
	at org.quiltmc.enigma.api.class_handle.ClassHandleProvider$Entry.lambda$continueMapSource$20(ClassHandleProvider.java:283)
	at org.quiltmc.enigma.util.Result.andThen(Result.java:81)
	at org.quiltmc.enigma.api.class_handle.ClassHandleProvider$Entry.lambda$continueMapSource$21(ClassHandleProvider.java:283)
	at java.base/java.util.concurrent.CompletableFuture$UniApply.tryFire(CompletableFuture.java:646)
	... 6 more

After restarting Enigma, I named a few without issue, then it started happening again for each rename.

Similar to #242, it works fine if I click retry.

Sometimes it dismisses the error on its own (auto-retries?).

enigma-soft-crash-param-names.mp4

[supersaiyansubtlety]

Combining this issue with #242, see #242 (comment)