IDEA 2020.3: Light files should have PSI only in one project

[carymrobbins]

In the latest release I am now seeing these exceptions -

java.lang.Throwable: Light files should have PSI only in one project, existing=com.intellij.psi.SingleRootFileViewProvider{vFile=LightVirtualFile: /Core.hs, content=VirtualFileContent{size=18159}, eventSystemEnabled=false} in Project(name=project, containerState=COMPONENT_CREATED, componentStore=/Users/me/project), requested in Project(name=intellij-haskforce, containerState=COMPONENT_CREATED, componentStore=/Users/crobbins/projects/intellij-haskforce)
	at com.intellij.openapi.diagnostic.Logger.error(Logger.java:159)
	at com.intellij.psi.impl.file.impl.FileManagerImpl.checkHasNoOtherPsi(FileManagerImpl.java:205)
	at com.intellij.psi.impl.file.impl.FileManagerImpl.findViewProvider(FileManagerImpl.java:194)
	at com.intellij.psi.impl.file.impl.FileManagerImpl.findFile(FileManagerImpl.java:368)
	at com.intellij.psi.impl.PsiManagerImpl.findFile(PsiManagerImpl.java:154)
	at com.haskforce.codeInsight.HaskellCompletionCacheLoader$Handler.$anonfun$fileContentLoaded$1(HaskellCompletionCacheLoader.scala:67)
	at com.intellij.openapi.application.impl.ApplicationImpl.runReadAction(ApplicationImpl.java:855)
	at com.haskforce.codeInsight.HaskellCompletionCacheLoader$Handler.fileContentLoaded(HaskellCompletionCacheLoader.scala:66)
	at jdk.internal.reflect.GeneratedMethodAccessor108.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at com.intellij.util.messages.impl.MessageBusImpl.invokeListener(MessageBusImpl.java:652)
	at com.intellij.util.messages.impl.MessageBusImpl.deliverMessage(MessageBusImpl.java:426)
	at com.intellij.util.messages.impl.MessageBusImpl.pumpWaitingBuses(MessageBusImpl.java:397)
	at com.intellij.util.messages.impl.MessageBusImpl.pumpMessages(MessageBusImpl.java:383)
	at com.intellij.util.messages.impl.MessageBusImpl.access$100(MessageBusImpl.java:33)
	at com.intellij.util.messages.impl.MessageBusImpl$MessagePublisher.invoke(MessageBusImpl.java:182)
	at com.sun.proxy.$Proxy87.documentCreated(Unknown Source)
	at com.intellij.psi.impl.PsiDocumentManagerBase.fireDocumentCreated(PsiDocumentManagerBase.java:728)
	at com.intellij.psi.impl.PsiDocumentManagerImpl$1.fileContentLoaded(PsiDocumentManagerImpl.java:56)
	at jdk.internal.reflect.GeneratedMethodAccessor108.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at com.intellij.util.messages.impl.MessageBusImpl.invokeListener(MessageBusImpl.java:652)
	at com.intellij.util.messages.impl.MessageBusImpl.deliverMessage(MessageBusImpl.java:426)
	at com.intellij.util.messages.impl.MessageBusImpl.pumpWaitingBuses(MessageBusImpl.java:401)
	at com.intellij.util.messages.impl.MessageBusImpl.pumpMessages(MessageBusImpl.java:383)
	at com.intellij.util.messages.impl.MessageBusImpl.access$100(MessageBusImpl.java:33)
	at com.intellij.util.messages.impl.MessageBusImpl$MessagePublisher.invoke(MessageBusImpl.java:189)
	at com.sun.proxy.$Proxy27.fileContentLoaded(Unknown Source)
	at jdk.internal.reflect.GeneratedMethodAccessor108.invoke(Unknown Source)
	at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.base/java.lang.reflect.Method.invoke(Method.java:566)
	at com.intellij.openapi.fileEditor.impl.FileDocumentManagerImpl.multiCast(FileDocumentManagerImpl.java:172)
	at com.intellij.openapi.fileEditor.impl.FileDocumentManagerImpl.lambda$new$0(FileDocumentManagerImpl.java:127)
	at com.sun.proxy.$Proxy27.fileContentLoaded(Unknown Source)
	at com.intellij.openapi.fileEditor.impl.FileDocumentManagerImpl.fileContentLoaded(FileDocumentManagerImpl.java:847)
	at com.intellij.openapi.fileEditor.impl.FileDocumentManagerBase.getDocument(FileDocumentManagerBase.java:70)
	at com.intellij.psi.AbstractFileViewProvider.getDocument(AbstractFileViewProvider.java:180)
	at com.intellij.codeInsight.completion.CompletionInitializationUtil.obtainFileCopy(CompletionInitializationUtil.java:272)
	at com.intellij.codeInsight.completion.CompletionInitializationUtil.doInsertDummyIdentifier(CompletionInitializationUtil.java:140)
	at com.intellij.codeInsight.completion.CompletionInitializationUtil.insertDummyIdentifier(CompletionInitializationUtil.java:117)
	at com.intellij.codeInsight.completion.CodeCompletionHandlerBase.lambda$scheduleContributorsAfterAsyncCommit$4(CodeCompletionHandlerBase.java:290)
	at com.intellij.openapi.application.impl.NonBlockingReadActionImpl$Submission.insideReadAction(NonBlockingReadActionImpl.java:521)
	at com.intellij.openapi.application.impl.NonBlockingReadActionImpl$Submission.lambda$attemptComputation$3(NonBlockingReadActionImpl.java:468)
	at com.intellij.openapi.application.impl.ApplicationImpl.tryRunReadAction(ApplicationImpl.java:1137)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.lambda$runInReadActionWithWriteActionPriority$0(ProgressIndicatorUtils.java:76)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.runActionAndCancelBeforeWrite(ProgressIndicatorUtils.java:152)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.lambda$runWithWriteActionPriority$1(ProgressIndicatorUtils.java:113)
	at com.intellij.openapi.progress.ProgressManager.lambda$runProcess$0(ProgressManager.java:59)
	at com.intellij.openapi.progress.impl.CoreProgressManager.lambda$runProcess$2(CoreProgressManager.java:178)
	at com.intellij.openapi.progress.impl.CoreProgressManager.registerIndicatorAndRun(CoreProgressManager.java:658)
	at com.intellij.openapi.progress.impl.CoreProgressManager.executeProcessUnderProgress(CoreProgressManager.java:610)
	at com.intellij.openapi.progress.impl.ProgressManagerImpl.executeProcessUnderProgress(ProgressManagerImpl.java:65)
	at com.intellij.openapi.progress.impl.CoreProgressManager.runProcess(CoreProgressManager.java:165)
	at com.intellij.openapi.progress.ProgressManager.runProcess(ProgressManager.java:59)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.runWithWriteActionPriority(ProgressIndicatorUtils.java:110)
	at com.intellij.openapi.progress.util.ProgressIndicatorUtils.runInReadActionWithWriteActionPriority(ProgressIndicatorUtils.java:76)
	at com.intellij.openapi.application.impl.NonBlockingReadActionImpl$Submission.attemptComputation(NonBlockingReadActionImpl.java:486)
	at com.intellij.openapi.application.impl.NonBlockingReadActionImpl$Submission.lambda$transferToBgThread$1(NonBlockingReadActionImpl.java:408)
	at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
	at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:668)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1$1.run(Executors.java:665)
	at java.base/java.security.AccessController.doPrivileged(Native Method)
	at java.base/java.util.concurrent.Executors$PrivilegedThreadFactory$1.run(Executors.java:665)
	at java.base/java.lang.Thread.run(Thread.java:834)