roslyn: Extract-method C7 crash

i was trying to extract the following code:

                    if (method != null &&
                        method.DeclaredAccessibility == Accessibility.Public &&
                        method.IsStatic &&
                        _regexType.Equals(method.ContainingType))
                    {
                        return AnalyzeStringLiteral(
                            stringLiteral, argumentNode, cancellationToken, out options);
                    }

                    return true;

Callstack:

System.InvalidOperationException : Matrix does not contain Key 'C7'.
   at Roslyn.Utilities.Contract.ThrowIfFalse(Boolean condition,String message)
   at Microsoft.CodeAnalysis.ExtractMethod.ExtractMethodMatrix.GetVariableStyle(Boolean captured,Boolean dataFlowIn,Boolean dataFlowOut,Boolean alwaysAssigned,Boolean variableDeclared,Boolean readInside,Boolean writtenInside,Boolean readOutside,Boolean writtenOutside,Boolean unsafeAddressTaken)
   at Microsoft.CodeAnalysis.ExtractMethod.MethodExtractor.Analyzer.GetVariableStyle(Dictionary`2 symbolMap,ISymbol symbol,SemanticModel model,ITypeSymbol type,Boolean captured,Boolean dataFlowIn,Boolean dataFlowOut,Boolean alwaysAssigned,Boolean variableDeclared,Boolean readInside,Boolean writtenInside,Boolean readOutside,Boolean writtenOutside,Boolean unsafeAddressTaken)
   at Microsoft.CodeAnalysis.ExtractMethod.MethodExtractor.Analyzer.GenerateVariableInfoMap(SemanticModel model,DataFlowAnalysis dataFlowAnalysisData,Dictionary`2 symbolMap)
   at async Microsoft.CodeAnalysis.ExtractMethod.MethodExtractor.Analyzer.AnalyzeAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.ExtractMethod.MethodExtractor.ExtractMethodAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.ExtractMethod.AbstractExtractMethodService`3.ExtractMethodAsync[TValidator,TExtractor,TResult](<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.CodeRefactorings.ExtractMethod.ExtractMethodCodeRefactoringProvider.GetCodeActionAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.CodeRefactorings.ExtractMethod.ExtractMethodCodeRefactoringProvider.ComputeRefactoringsAsync(<Unknown Parameters>)
   at async Microsoft.CodeAnalysis.CodeRefactorings.CodeRefactoringService.GetRefactoringFromProviderAsync(<Unknown Parameters>)