Debug.Assert: NullableWalker.VisitConditionalOperatorCore

[complog (msft-internal only)](https://microsoft-my.sharepoint.com/:u:/p/frsilb/IQDdEPn2Y0QtTL-v_2XmwpBkAdojNxYPlFbU1_YGrCf5iQw?e=LF6p88)

```
Assertion failed.
_returnTypesOpt is not null || _disableDiagnostics
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitConditionalOperatorCore(BoundExpression node, Boolean isRef, BoundExpression condition, BoundExpression originalConsequence, BoundExpression originalAlternative) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 6549
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitUnconvertedConditionalOperator(BoundUnconvertedConditionalOperator node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 3322
at Microsoft.CodeAnalysis.CSharp.BoundUnconvertedConditionalOperator.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 2028
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitExpressionOrPatternWithoutStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 374
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitExpressionOrPatternWithoutStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3739
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.VisitExpressionOrPatternWithStackGuard(Int32& recursionDepth, BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 213
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 365
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitArgumentEvaluate(BoundExpression argument, RefKind refKind, FlowAnalysisAnnotations annotations) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 8088
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitArgumentsEvaluate(ImmutableArray`1 arguments, ImmutableArray`1 refKindsOpt, ImmutableArray`1 parameterAnnotationsOpt, BitVector defaultArguments, Nullable`1 firstArgumentResult) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 8049
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitArgumentsCore[TMember](BoundNode node, ImmutableArray`1 arguments, ImmutableArray`1 refKindsOpt, ImmutableArray`1 parametersOpt, ImmutableArray`1 argsToParamsOpt, BitVector defaultArguments, Boolean expanded, Boolean usesExtensionReceiver, TMember member, Boolean delayCompletionForTargetMember, Nullable`1 firstArgumentResult) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 7545
at Microsoft.CodeAnalysis.CSharp.NullableWalker.ReInferMethodAndVisitArguments(BoundNode node, BoundExpression receiverOpt, TypeWithState receiverType, MethodSymbol method, ImmutableArray`1 arguments, ImmutableArray`1 refKindsOpt, ImmutableArray`1 argsToParamsOpt, BitVector defaultArguments, Boolean expanded, Boolean invokedAsExtensionMethod, Nullable`1 firstArgumentResult) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 6965
at Microsoft.CodeAnalysis.CSharp.NullableWalker.g__reinferMethodAndVisitArguments|234_2(BoundCall node, TypeWithState receiverType, Nullable`1 firstArgumentResult) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 6892
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitCall(BoundCall node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 6834
at Microsoft.CodeAnalysis.CSharp.BoundCall.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 6276
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitExpressionOrPatternWithoutStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 374
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitExpressionOrPatternWithoutStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3739
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.VisitExpressionOrPatternWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 244
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.VisitExpressionOrPatternWithStackGuard(Int32& recursionDepth, BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 217
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 365
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitRvalue(BoundExpression node, Boolean isKnownToBeAnLvalue) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 2320
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitExpressionStatement(BoundExpressionStatement node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 1375
at Microsoft.CodeAnalysis.CSharp.BoundExpressionStatement.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 3740
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 368
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitStatement(BoundStatement statement) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 672
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitStatement(BoundStatement statement) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3868
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitStatementsWithLocalFunctions(BoundBlock block) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3327
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitBlock(BoundBlock node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3230
at Microsoft.CodeAnalysis.CSharp.BoundBlock.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 3380
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 368
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitStatement(BoundStatement statement) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 672
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitStatement(BoundStatement statement) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3868
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitIfStatement(BoundIfStatement node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 1832
at Microsoft.CodeAnalysis.CSharp.BoundIfStatement.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 3928
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 368
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitStatement(BoundStatement statement) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 672
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitStatement(BoundStatement statement) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3868
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitStatementsWithLocalFunctions(BoundBlock block) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3327
at Microsoft.CodeAnalysis.CSharp.NullableWalker.VisitBlock(BoundBlock node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3230
at Microsoft.CodeAnalysis.CSharp.BoundBlock.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 3380
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 368
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitMethodBodies(BoundBlock blockBody, BoundBlock expressionBody) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 3902
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitNonConstructorMethodBody(BoundNonConstructorMethodBody node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 3795
at Microsoft.CodeAnalysis.CSharp.BoundNonConstructorMethodBody.Accept(BoundTreeVisitor visitor) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Generated/BoundNodes.xml.Generated.cs:line 8954
at Microsoft.CodeAnalysis.CSharp.BoundTreeVisitor.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/BoundTree/BoundTreeVisitors.cs:line 151
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitWithStackGuard(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 368
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.VisitAlways(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 353
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 342
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node, Boolean expressionIsRead) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3859
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Visit(BoundNode node) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 3828
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Scan(Boolean& badRegion) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 424
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Scan(Boolean& badRegion) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 640
at Microsoft.CodeAnalysis.CSharp.AbstractFlowPass`2.Analyze(Boolean& badRegion, Optional`1 initialState) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/AbstractFlowPass.cs:line 447
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Analyze(NullableWalker walker, Symbol symbol, DiagnosticBag diagnostics, Optional`1 initialState, Builder snapshotBuilderOpt, Boolean requiresAnalysis) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 1912
at Microsoft.CodeAnalysis.CSharp.NullableWalker.Analyze(CSharpCompilation compilation, Symbol symbol, BoundNode node, Binder binder, Conversions conversions, DiagnosticBag diagnostics, Boolean useConstructorExitWarnings, Nullable`1 getterNullResilienceData, Boolean useDelegateInvokeParameterTypes, Boolean useDelegateInvokeReturnType, MethodSymbol delegateInvokeMethodOpt, VariableState initialState, MethodSymbol baseOrThisInitializer, Builder analyzedNullabilityMapOpt, Builder snapshotBuilderOpt, ArrayBuilder`1 returnTypesOpt, Boolean getFinalNullableState, VariableState& finalNullableState, Boolean requiresAnalysis) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 1880
at Microsoft.CodeAnalysis.CSharp.NullableWalker.AnalyzeWithSemanticInfo(CSharpCompilation compilation, Symbol symbol, BoundNode node, Binder binder, VariableState initialState, DiagnosticBag diagnostics, Boolean createSnapshots, Boolean requiresAnalysis) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 1631
at Microsoft.CodeAnalysis.CSharp.NullableWalker.AnalyzeAndRewrite(CSharpCompilation compilation, Symbol symbol, BoundNode node, Binder binder, VariableState initialState, DiagnosticBag diagnostics, Boolean createSnapshots, SnapshotManager& snapshotManager, ImmutableDictionary`2& remappedSymbols) in /home/fred/git/r2/src/Compilers/CSharp/Portable/FlowAnalysis/NullableWalker.cs:line 1611
at Microsoft.CodeAnalysis.CSharp.MethodCompiler.BindMethodBody(MethodSymbol method, TypeCompilationState compilationState, BindingDiagnosticBag diagnostics, Boolean includeInitializersInBody, BoundNode initializersBody, Boolean reportNullableDiagnostics, ImportChain& importChain, Boolean& originalBodyNested, Boolean& prependedDefaultValueTypeConstructorInitializer, InitialState& forSemanticModel) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs:line 1961
at Microsoft.CodeAnalysis.CSharp.MethodCompiler.CompileMethod(MethodSymbol methodSymbol, Int32 methodOrdinal, ProcessedFieldInitializers& processedInitializers, SynthesizedSubmissionFields previousSubmissionFields, TypeCompilationState compilationState) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs:line 1056
at Microsoft.CodeAnalysis.CSharp.MethodCompiler.CompileNamedType(NamedTypeSymbol containingType) in /home/fred/git/r2/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs:line 561
at Microsoft.CodeAnalysis.CSharp.MethodCompiler.<>c__DisplayClass25_0.b__0() in /home/fred/git/r2/src/Compilers/CSharp/Portable/Compiler/MethodCompiler.cs:line 446
at Roslyn.Utilities.UICultureUtilities.<>c__DisplayClass5_0.b__0() in /home/fred/git/r2/src/Compilers/Core/Portable/InternalUtilities/UICultureUtilities.cs:line 139
at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
at System.Threading.ThreadPoolWorkQueue.Dispatch()
at System.Threading.PortableThreadPool.WorkerThread.WorkerThreadStart()
at System.Threading.Thread.StartCallback()
```