NullReferenceException in analyzer

[WalkerCodeRanger]

System.NullReferenceException: Object reference not set to an instance of an object.
    at ExhaustiveMatching.Analyzer.TypeSymbolExtensions.GetFullName(ISymbol symbol)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.GetTypeSymbolMatched(SyntaxNodeAnalysisContext context, ITypeSymbol type, CasePatternSwitchLabelSyntax casePattern, HashSet`1 allCases, Boolean isClosed)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.<>c__DisplayClass3_0.<AnalyzeSwitchOnClosed>b__1(CasePatternSwitchLabelSyntax casePattern)
    at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
    at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext()
    at System.Collections.Immutable.DisposableEnumeratorAdapter`2.MoveNext()
    at System.Collections.Immutable.ImmutableHashSet`1.Union(IEnumerable`1 other, MutationInput origin)
    at System.Collections.Immutable.ImmutableHashSet`1.Union(IEnumerable`1 items, Boolean avoidWithComparer)
    at System.Collections.Immutable.ImmutableHashSet`1.Union(IEnumerable`1 other)
    at System.Collections.Immutable.ImmutableHashSet.ToImmutableHashSet[TSource](IEnumerable`1 source, IEqualityComparer`1 equalityComparer)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.AnalyzeSwitchOnClosed(SyntaxNodeAnalysisContext context, SwitchStatementSyntax switchStatement, ITypeSymbol type)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.Analyze(SyntaxNodeAnalysisContext context, SwitchStatementSyntax switchStatement)
    at ExhaustiveMatching.Analyzer.ExhaustiveMatchAnalyzer.AnalyzeSwitchStatement(SyntaxNodeAnalysisContext context)

[WalkerCodeRanger]

System.NullReferenceException: Object reference not set to an instance of an object.
    at ExhaustiveMatching.Analyzer.TypeSymbolExtensions.GetFullName(ISymbol symbol)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.GetTypeSymbolMatched(SyntaxNodeAnalysisContext context, ITypeSymbol type, CasePatternSwitchLabelSyntax casePattern, HashSet`1 allCases, Boolean isClosed)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.<>c__DisplayClass3_0.<AnalyzeSwitchOnClosed>b__1(CasePatternSwitchLabelSyntax casePattern)
    at System.Linq.Enumerable.WhereSelectEnumerableIterator`2.MoveNext()
    at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext()
    at System.Collections.Immutable.DisposableEnumeratorAdapter`2.MoveNext()
    at System.Collections.Immutable.ImmutableHashSet`1.Union(IEnumerable`1 other, MutationInput origin)
    at System.Collections.Immutable.ImmutableHashSet`1.Union(IEnumerable`1 items, Boolean avoidWithComparer)
    at System.Collections.Immutable.ImmutableHashSet`1.Union(IEnumerable`1 other)
    at System.Collections.Immutable.ImmutableHashSet.ToImmutableHashSet[TSource](IEnumerable`1 source, IEqualityComparer`1 equalityComparer)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.AnalyzeSwitchOnClosed(SyntaxNodeAnalysisContext context, SwitchStatementSyntax switchStatement, ITypeSymbol type)
    at ExhaustiveMatching.Analyzer.SwitchStatementAnalyzer.Analyze(SyntaxNodeAnalysisContext context, SwitchStatementSyntax switchStatement)
    at ExhaustiveMatching.Analyzer.ExhaustiveMatchAnalyzer.AnalyzeSwitchStatement(SyntaxNodeAnalysisContext context)

[WalkerCodeRanger]

Note: this GetFullName has moved to SymbolExtensions.GetFullName() and GetTypeSymbolMatched has moved to PatternAnalyzer.GetMatchedTypeSymbol()

[APIWT]

Do you have some code to reproduce this? I might have some time soon to attempt to look at it.

[WalkerCodeRanger]

Thanks for the offer to help!

No, unfortunately, I don't have code to reproduce this. That is a big part of why it isn't already fixed. I also haven't seen the error myself in a while. I believe it is caused by C# code that has other compile errors in it. I captured these stack traces from the Visual Studio error panel. I'd be editing code and then find that at some point one of these occurred. But then I'd close and reopen Visual Studio and it would go away. The code that caused it having been already edited out of existence by fixing other bugs. So, I think when the code is invalid, some invariant I'm thinking would always hold no longer holds, and thus something is null. But I don't know what and why.