AbstractLibraryManager caused a model update that threw NPE downstream

## What happened

Was just updating markdown file when I noticed this. I did have open debugging connection to ios device.

## Version information

IntelliJ IDEA `2021.1.3` • Flutter plugin `io.flutter 58.0.3` • Dart plugin `211.7727`

Flutter 2.2.3 • channel stable • https://github.com/flutter/flutter.git
Framework • revision f4abaa0735 (5 weeks ago) • 2021-07-01 12:46:11 -0700
Engine • revision 241c87ad80
Tools • Dart 2.13.4

## Exception

Check after add Diff

Entity source filter: null

Version: v16.1
Saving store content at: /Users/egaga/Library/Logs/JetBrains/IntelliJIdea2021.1/workspaceModel/storeDump-20210804-124521

```
java.lang.NullPointerException
at com.intellij.workspaceModel.storage.impl.references.OneToOneChild$NotNull.getValue(OneToOne.kt:45)
at com.intellij.workspaceModel.storage.bridgeEntities.LibraryPropertiesEntity.getLibrary(bridgeModelEntities.kt)
at com.intellij.workspaceModel.storage.bridgeEntities.LibraryPropertiesEntityData.assertConsistency(bridgeModelEntities.kt:603)
at com.intellij.workspaceModel.storage.impl.EntitiesBarrel.assertConsistency(EntitiesBarrel.kt:130)
at com.intellij.workspaceModel.storage.impl.AbstractEntityStorage.assertConsistency$intellij_platform_workspaceModel_storage(WorkspaceEntityStorageImpl.kt:848)
at com.intellij.workspaceModel.storage.impl.AbstractEntityStorage.assertConsistencyInStrictMode$intellij_platform_workspaceModel_storage(WorkspaceEntityStorageImpl.kt:974)
at com.intellij.workspaceModel.storage.impl.AddDiffOperation.addDiff(AddDiffOperation.kt:87)
at com.intellij.workspaceModel.storage.impl.WorkspaceEntityStorageBuilderImpl.addDiff(WorkspaceEntityStorageImpl.kt:640)
at com.intellij.workspaceModel.ide.impl.legacyBridge.library.LibraryModifiableModelBridgeImpl$commit$1.invoke(LibraryModifiableModelBridgeImpl.kt:98)
at com.intellij.workspaceModel.ide.impl.legacyBridge.library.LibraryModifiableModelBridgeImpl$commit$1.invoke(LibraryModifiableModelBridgeImpl.kt:29)
at com.intellij.workspaceModel.ide.impl.WorkspaceModelImpl.updateProjectModel(WorkspaceModelImpl.kt:86)
at com.intellij.workspaceModel.ide.impl.legacyBridge.library.LibraryModifiableModelBridgeImpl.commit(LibraryModifiableModelBridgeImpl.kt:97)
at com.intellij.openapi.application.impl.ApplicationImpl.runWriteAction(ApplicationImpl.java:959)
at io.flutter.sdk.AbstractLibraryManager.lambda$updateLibraryContent$2(AbstractLibraryManager.java:100)
at com.intellij.openapi.project.DumbServiceImpl.doUnsafeRunWhenSmart(DumbServiceImpl.java:258)
at com.intellij.openapi.project.DumbServiceImpl.lambda$runWhenSmart$0(DumbServiceImpl.java:244)
at com.intellij.ide.startup.impl.StartupManagerImpl.runAfterOpened(StartupManagerImpl.java:503)
at com.intellij.openapi.project.DumbServiceImpl.runWhenSmart(DumbServiceImpl.java:244)
at io.flutter.sdk.AbstractLibraryManager.lambda$updateLibraryContent$3(AbstractLibraryManager.java:99)
at com.intellij.openapi.application.impl.ApplicationImpl.runWriteAction(ApplicationImpl.java:959)
at io.flutter.sdk.AbstractLibraryManager.updateLibraryContent(AbstractLibraryManager.java:84)
at io.flutter.sdk.AbstractLibraryManager.updateLibraryContent(AbstractLibraryManager.java:57)
at io.flutter.sdk.FlutterPluginsLibraryManager.updateFlutterPluginsImpl(FlutterPluginsLibraryManager.java:119)
at io.flutter.sdk.FlutterPluginsLibraryManager.updateFlutterPlugins(FlutterPluginsLibraryManager.java:106)
at com.intellij.openapi.project.DumbServiceImpl.lambda$smartInvokeLater$9(DumbServiceImpl.java:532)
at com.intellij.openapi.application.TransactionGuardImpl.runWithWritingAllowed(TransactionGuardImpl.java:218)
at com.intellij.openapi.application.TransactionGuardImpl.access$200(TransactionGuardImpl.java:21)
at com.intellij.openapi.application.TransactionGuardImpl$2.run(TransactionGuardImpl.java:200)
at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:781)
at com.intellij.openapi.application.impl.ApplicationImpl.lambda$invokeLater$4(ApplicationImpl.java:319)
at com.intellij.openapi.application.impl.FlushQueue.doRun(FlushQueue.java:84)
at com.intellij.openapi.application.impl.FlushQueue.runNextEvent(FlushQueue.java:133)
at com.intellij.openapi.application.impl.FlushQueue.flushNow(FlushQueue.java:46)
at com.intellij.openapi.application.impl.FlushQueue$FlushNow.run(FlushQueue.java:189)
at java.desktop/java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:313)
at java.desktop/java.awt.EventQueue.dispatchEventImpl(EventQueue.java:776)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:727)
at java.desktop/java.awt.EventQueue$4.run(EventQueue.java:721)
at java.base/java.security.AccessController.doPrivileged(Native Method)
at java.base/java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:85)
at java.desktop/java.awt.EventQueue.dispatchEvent(EventQueue.java:746)
at com.intellij.ide.IdeEventQueue.defaultDispatchEvent(IdeEventQueue.java:969)
at com.intellij.ide.IdeEventQueue._dispatchEvent(IdeEventQueue.java:839)
at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$8(IdeEventQueue.java:449)
at com.intellij.openapi.progress.impl.CoreProgressManager.computePrioritized(CoreProgressManager.java:808)
at com.intellij.ide.IdeEventQueue.lambda$dispatchEvent$9(IdeEventQueue.java:448)
at com.intellij.openapi.application.impl.ApplicationImpl.runIntendedWriteActionOnCurrentThread(ApplicationImpl.java:781)
at com.intellij.ide.IdeEventQueue.dispatchEvent(IdeEventQueue.java:496)
at java.desktop/java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:203)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:124)
at java.desktop/java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:113)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:109)
at java.desktop/java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.desktop/java.awt.EventDispatchThread.run(EventDispatchThread.java:90)
```