internal error: Index was outside the bounds of the array

[0x53A]

For me this happens reproducible when editing Program.fs in the FAKE solution.

Callstack:

1. => throw new ErrorLogger.UnresolvedPathReferenceNoRange(this.name@, data)

>	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.Tast.CcuThunk.EnsureDerefable(string[] requiringPath) (IL=~0x0021, Native=0x2DE3FB48+0x58)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.Tast.NonLocalEntityRef.TryDeref(bool canError) (IL=~0x0012, Native=0x2DE3A080+0x2D)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.Tast.EntityRef.get_Deref() (IL=~0x0015, Native=0x2DE31238+0x3E)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.Tastops.stripTyEqnsA(Microsoft.FSharp.Compiler.TcGlobals.TcGlobals g, bool canShortcut, Microsoft.FSharp.Compiler.Tast.TType ty) (IL=~0x002A, Native=0x2DE35B10+0x51)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.SymbolHelpers.f@114-75(Microsoft.FSharp.Compiler.TcGlobals.TcGlobals g, Microsoft.FSharp.Compiler.NameResolution.Item item, Microsoft.FSharp.Core.Unit unitVar0) (IL=~0x0012, Native=0x3160F400+0x22)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.SymbolHelpers.ItemDisplayPartialEquality@703.System-Collections-Generic-IEqualityComparer`1-GetHashCode(Microsoft.FSharp.Compiler.NameResolution.Item obj) (IL=Prolog, Native=0x3160F388+0x20)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.IPartialEqualityComparer.On@1094<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst, Microsoft.FSharp.Compiler.NameResolution.Item>.System-Collections-Generic-IEqualityComparer`1-GetHashCode(Microsoft.FSharp.Compiler.NameResolution.ItemWithInst obj) (IL=Epilog, Native=0x3160F2A8+0x39)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.IPartialEqualityComparer.wper@1108<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst>.System-Collections-Generic-IEqualityComparer`1-GetHashCode(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.IPartialEqualityComparer.WrapType<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> obj) (IL=Epilog, Native=0x3160F260+0x2F)
 	mscorlib.dll!System.Collections.Generic.Dictionary<Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.IPartialEqualityComparer.WrapType<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst>, object>.FindEntry(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.IPartialEqualityComparer.WrapType<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> key) (IL=~0x0016, Native=0x7184CDC0+0x47)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.IPartialEqualityComparer.partialDistinctBy@1114<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst>.Invoke(Microsoft.FSharp.Compiler.NameResolution.ItemWithInst v) (IL=~0x0016, Native=0x3160EF90+0x67)
 	FSharp.Core.dll!Microsoft.FSharp.Primitives.Basics.List.filterToFreshConsTail<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst>(Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> cons, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst, bool> f, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> l) (IL=~0x0019, Native=0x1803D378+0x2E)
 	FSharp.Core.dll!Microsoft.FSharp.Primitives.Basics.List.filter<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst>(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst, bool> predicate, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> l) (IL=0x005B, Native=0x1803D3F4+0xB7)
 	FSharp.Core.dll!Microsoft.FSharp.Collections.ListModule.Filter<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst>(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst, bool> predicate, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> list) (IL=Epilog, Native=0x180382E0+0x31)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.SymbolHelpers.RemoveDuplicateItems(Microsoft.FSharp.Compiler.TcGlobals.TcGlobals g, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.NameResolution.ItemWithInst> items) (IL=Epilog, Native=0x3160EA40+0x55)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetEnvironmentLookupResolutions(Microsoft.FSharp.Compiler.NameResolution.NameResolutionEnv nenv, Microsoft.FSharp.Compiler.AccessibilityLogic.AccessorDomain ad, Microsoft.FSharp.Compiler.Range.range m, Microsoft.FSharp.Collections.FSharpList<string> plid, Microsoft.FSharp.Compiler.NameResolution.TypeNameResolutionFlag filterCtors, bool showObsolete) (IL=~0x002A, Native=0x315AE3C0+0xB5)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetDeclaredItems<string>(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpParseFileResults> parseResultsOpt, string lineStr, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Collections.FSharpList<string>> origLongIdentOpt, int colAtEndOfNamesAndResidue, Microsoft.FSharp.Core.FSharpOption<string> residueOpt, int line, int loc, Microsoft.FSharp.Compiler.NameResolution.TypeNameResolutionFlag filterCtors, Microsoft.FSharp.Compiler.SourceCodeServices.ResolveOverloads resolveOverloads, Microsoft.FSharp.Core.FSharpFunc<System.Tuple<object, Microsoft.FSharp.Compiler.Range.range>, bool> hasTextChangedSinceLastTypecheck, bool isInRangeOperator, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>> allSymbols) (IL=~0x0354, Native=0x315A9CC8+0x66F)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetDeclItemsForNamesAtPosition(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpParseFileResults> parseResultsOpt, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Collections.FSharpList<string>> origLongIdentOpt, Microsoft.FSharp.Core.FSharpOption<string> residueOpt, int line, string lineStr, int colAtEndOfNamesAndResidue, Microsoft.FSharp.Compiler.NameResolution.TypeNameResolutionFlag filterCtors, Microsoft.FSharp.Compiler.SourceCodeServices.ResolveOverloads resolveOverloads, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>> getAllSymbols, Microsoft.FSharp.Core.FSharpFunc<System.Tuple<object, Microsoft.FSharp.Compiler.Range.range>, bool> hasTextChangedSinceLastTypecheck) (IL=~0x0050, Native=0x315A5790+0x14F)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.GetDeclarations@904.Invoke(Microsoft.FSharp.Core.Unit unitVar0) (IL=0x0061, Native=0x1AFBE6D8+0x72)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.ErrorScope.Protect<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo>(Microsoft.FSharp.Compiler.Range.range m, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo> f, Microsoft.FSharp.Core.FSharpFunc<string, Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo> err) (IL=~0x0008, Native=0x314C1BF8+0x4F)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetDeclarations(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpParseFileResults> parseResultsOpt, int line, string lineStr, int colAtEndOfNamesAndResidue, Microsoft.FSharp.Collections.FSharpList<string> qualifyingNames, string partialName, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>> getAllSymbols, Microsoft.FSharp.Core.FSharpFunc<System.Tuple<object, Microsoft.FSharp.Compiler.Range.range>, bool> hasTextChangedSinceLastTypecheck) (IL=Epilog, Native=0x1AFBE1A0+0x90)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.GetDeclarationListInfo@1817.Invoke(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok, Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo scope) (IL=Epilog, Native=0x1AFBE160+0x26)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.clo@1795-246<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo>.Invoke(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok) (IL=~0x0001, Native=0x314CFD50+0x3E)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Reactor.EnqueueAndAwaitOpAsync@176-2<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo>.Invoke(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok) (IL=~0x0008, Native=0x25F22210+0x36)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Reactor.loop@72-104.Invoke(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.ReactorCommands> _arg2) (IL=0x0301, Native=0x2662BE68+0x4C0)
 	FSharp.Core.dll!Microsoft.FSharp.Control.AsyncBuilderImpl.args@823-1<Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.ReactorCommands>, Microsoft.FSharp.Core.Unit>.Invoke(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.ReactorCommands> a) (IL=~0x0016, Native=0x180BCD0C+0x40)
 	FSharp.Core.dll!<StartupCode$FSharp-Core>.$Control.loop@425-51(Microsoft.FSharp.Control.Trampoline @this, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Control.FakeUnitValue> action) (IL=~0x0001, Native=0x180817A4+0x28)
 	FSharp.Core.dll!Microsoft.FSharp.Control.Trampoline.ExecuteAction(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Control.FakeUnitValue> firstAction) (IL=~0x0018, Native=0x18081664+0x56)
 	FSharp.Core.dll!Microsoft.FSharp.Control.TrampolineHolder.Protect(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Control.FakeUnitValue> firstAction) (IL=Epilog, Native=0x1808256C+0x4C)
 	FSharp.Core.dll!<StartupCode$FSharp-Core>.$Control.AwaitWaitHandle@1760-2.Invoke(object state, bool timedOut) (IL=Epilog, Native=0x18082660+0xE8)
 	mscorlib.dll!System.Threading._ThreadPoolWaitOrTimerCallback.WaitOrTimerCallback_Context(object state, bool timedOut) (IL=Epilog, Native=0x718C8E20+0x4B)
 	mscorlib.dll!System.Threading._ThreadPoolWaitOrTimerCallback.WaitOrTimerCallback_Context_f(object state) (IL=Epilog, Native=0x718C8DF0+0x1F)
 	mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) (IL=~0x0079, Native=0x718F9910+0xEA)
 	mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) (IL=Epilog, Native=0x718F98F0+0x16)
 	mscorlib.dll!System.Threading._ThreadPoolWaitOrTimerCallback.PerformWaitOrTimerCallback(object state, bool timedOut) (IL=~0x0042, Native=0x718C8CC0+0x93)
 	[Native to Managed Transition]

2. ==> IndexOutOfRangeException

>	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.clo@568-216.Invoke(Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol x) (IL=~0x0064, Native=0x1B05B050+0x1E9)
 	FSharp.Core.dll!Microsoft.FSharp.Core.OptionModule.Map<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol, Microsoft.FSharp.Compiler.SourceCodeServices.UnresolvedSymbol>(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol, Microsoft.FSharp.Compiler.SourceCodeServices.UnresolvedSymbol> mapping, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol> option) (IL=~0x000D, Native=0x18049220+0x24)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.CompletionItem(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.Tast.EntityRef> ty, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol> unresolvedEntity, Microsoft.FSharp.Compiler.NameResolution.ItemWithInst item) (IL=~0x00D1, Native=0x31623E48+0xE3)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.globalResult@751<string>.Invoke(Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol globalItem) (IL=Epilog, Native=0x1B05AF48+0xEF)
 	FSharp.Core.dll!Microsoft.FSharp.Primitives.Basics.List.mapToFreshConsTail<Microsoft.FSharp.Compiler.SourceCodeServices.CompletionItem, Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>(Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.CompletionItem> cons, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol, Microsoft.FSharp.Compiler.SourceCodeServices.CompletionItem> f, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol> x) (IL=~0x0019, Native=0x1803BB9C+0x36)
 	FSharp.Core.dll!Microsoft.FSharp.Primitives.Basics.List.map<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol, Microsoft.FSharp.Compiler.SourceCodeServices.CompletionItem>(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol, Microsoft.FSharp.Compiler.SourceCodeServices.CompletionItem> mapping, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol> x) (IL=0x0056, Native=0x1803BC40+0xEF)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetDeclaredItems<string>(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpParseFileResults> parseResultsOpt, string lineStr, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Collections.FSharpList<string>> origLongIdentOpt, int colAtEndOfNamesAndResidue, Microsoft.FSharp.Core.FSharpOption<string> residueOpt, int line, int loc, Microsoft.FSharp.Compiler.NameResolution.TypeNameResolutionFlag filterCtors, Microsoft.FSharp.Compiler.SourceCodeServices.ResolveOverloads resolveOverloads, Microsoft.FSharp.Core.FSharpFunc<System.Tuple<object, Microsoft.FSharp.Compiler.Range.range>, bool> hasTextChangedSinceLastTypecheck, bool isInRangeOperator, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>> allSymbols) (IL=~0x0625, Native=0x315A9CC8+0xCBC)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetDeclItemsForNamesAtPosition(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpParseFileResults> parseResultsOpt, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Collections.FSharpList<string>> origLongIdentOpt, Microsoft.FSharp.Core.FSharpOption<string> residueOpt, int line, string lineStr, int colAtEndOfNamesAndResidue, Microsoft.FSharp.Compiler.NameResolution.TypeNameResolutionFlag filterCtors, Microsoft.FSharp.Compiler.SourceCodeServices.ResolveOverloads resolveOverloads, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>> getAllSymbols, Microsoft.FSharp.Core.FSharpFunc<System.Tuple<object, Microsoft.FSharp.Compiler.Range.range>, bool> hasTextChangedSinceLastTypecheck) (IL=~0x0050, Native=0x315A5790+0x14F)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.GetDeclarations@904.Invoke(Microsoft.FSharp.Core.Unit unitVar0) (IL=0x0061, Native=0x1AFBE6D8+0x72)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.ErrorScope.Protect<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo>(Microsoft.FSharp.Compiler.Range.range m, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo> f, Microsoft.FSharp.Core.FSharpFunc<string, Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo> err) (IL=~0x0008, Native=0x314C1BF8+0x4F)
 	FSharp.Compiler.Private.dll!Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo.GetDeclarations(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok, Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpParseFileResults> parseResultsOpt, int line, string lineStr, int colAtEndOfNamesAndResidue, Microsoft.FSharp.Collections.FSharpList<string> qualifyingNames, string partialName, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Collections.FSharpList<Microsoft.FSharp.Compiler.SourceCodeServices.AssemblySymbol>> getAllSymbols, Microsoft.FSharp.Core.FSharpFunc<System.Tuple<object, Microsoft.FSharp.Compiler.Range.range>, bool> hasTextChangedSinceLastTypecheck) (IL=Epilog, Native=0x1AFBE1A0+0x90)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.GetDeclarationListInfo@1817.Invoke(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok, Microsoft.FSharp.Compiler.SourceCodeServices.TypeCheckInfo scope) (IL=Epilog, Native=0x1AFBE160+0x26)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Service.clo@1795-246<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo>.Invoke(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok) (IL=~0x0001, Native=0x314CFD50+0x3E)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Reactor.EnqueueAndAwaitOpAsync@176-2<Microsoft.FSharp.Compiler.SourceCodeServices.FSharpDeclarationListInfo>.Invoke(Microsoft.FSharp.Compiler.AbstractIL.Internal.Library.CompilationThreadToken ctok) (IL=~0x0008, Native=0x25F22210+0x36)
 	FSharp.Compiler.Private.dll!<StartupCode$FSharp-Compiler-Private>.$Reactor.loop@72-104.Invoke(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.ReactorCommands> _arg2) (IL=0x0301, Native=0x2662BE68+0x4C0)
 	FSharp.Core.dll!Microsoft.FSharp.Control.AsyncBuilderImpl.args@823-1<Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.ReactorCommands>, Microsoft.FSharp.Core.Unit>.Invoke(Microsoft.FSharp.Core.FSharpOption<Microsoft.FSharp.Compiler.SourceCodeServices.ReactorCommands> a) (IL=~0x0016, Native=0x180BCD0C+0x40)
 	FSharp.Core.dll!<StartupCode$FSharp-Core>.$Control.loop@425-51(Microsoft.FSharp.Control.Trampoline @this, Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Control.FakeUnitValue> action) (IL=~0x0001, Native=0x180817A4+0x28)
 	FSharp.Core.dll!Microsoft.FSharp.Control.Trampoline.ExecuteAction(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Control.FakeUnitValue> firstAction) (IL=~0x0018, Native=0x18081664+0x56)
 	FSharp.Core.dll!Microsoft.FSharp.Control.TrampolineHolder.Protect(Microsoft.FSharp.Core.FSharpFunc<Microsoft.FSharp.Core.Unit, Microsoft.FSharp.Control.FakeUnitValue> firstAction) (IL=Epilog, Native=0x1808256C+0x4C)
 	FSharp.Core.dll!<StartupCode$FSharp-Core>.$Control.AwaitWaitHandle@1760-2.Invoke(object state, bool timedOut) (IL=Epilog, Native=0x18082660+0xE8)
 	mscorlib.dll!System.Threading._ThreadPoolWaitOrTimerCallback.WaitOrTimerCallback_Context(object state, bool timedOut) (IL=Epilog, Native=0x718C8E20+0x4B)
 	mscorlib.dll!System.Threading._ThreadPoolWaitOrTimerCallback.WaitOrTimerCallback_Context_f(object state) (IL=Epilog, Native=0x718C8DF0+0x1F)
 	mscorlib.dll!System.Threading.ExecutionContext.RunInternal(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) (IL=~0x0079, Native=0x718F9910+0xEA)
 	mscorlib.dll!System.Threading.ExecutionContext.Run(System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, object state, bool preserveSyncCtx) (IL=Epilog, Native=0x718F98F0+0x16)
 	mscorlib.dll!System.Threading._ThreadPoolWaitOrTimerCallback.PerformWaitOrTimerCallback(object state, bool timedOut) (IL=~0x0042, Native=0x718C8CC0+0x93)
 	[Native to Managed Transition]

(I'm not sure if the first exception is even related, the second one is what gets bubbled to the UI)

[dsyme]

@0x53A Thanks, the second looks unrelated to the first, but should be fixed.

[auduchinok]

@0x53A Do you have completion of not in scope symbols enabled?

[0x53A]

@auduchinok

@0x53A Do you have completion of not in scope symbols enabled?

[auduchinok]

@0x53A Will completion work in this file with the last one disabled?

[0x53A]

@0x53A Will completion work in this file with the last one disabled?

yes.

Disabling the last one causes the issue to disappear. Didn't even need to restart VS.

[auduchinok]

Great. I've faced this behaviour today using a recent FCS build in Rider with such completion enabled.
The repro is very simple for me:

<Project Sdk="Microsoft.NET.Sdk">
  <PropertyGroup>
    <TargetFramework>netstandard2.0</TargetFramework>
  </PropertyGroup>
  <ItemGroup>
    <Compile Include="Library.fs" />
  </ItemGroup>
</Project>

module M

let x = <editor_caret>

[vasily-kirichenko]

Fixed in #3753, sorry for this bug.

[dsyme]

@vasily-kirichenko Thanks for fixing this!