warning AD0001: Analyzer 'Roslynator.CSharp.Analysis.InvocationExpressionAnalyzer' threw an exception of type 'System.NullReferenceException'

[baal2000]

Product and Version Used:
Roslynator.CSharp.Analysis

Released versions: 4.1.1 and earlier

Actual Behavior:
A conditional operator similar to:

   boolean_value ? "ab" : 'c'

where "ab" is a string value and 'c' is a char value causes

warning AD0001: Analyzer 'Roslynator.CSharp.Analysis.InvocationExpressionAnalyzer' threw an exception of type 'System.NullReferenceException' with message 'Object reference not set to an instance of an object.'. 

Expected Behavior:

error RCS1198: Avoid unnecessary boxing of value type. 

Steps to Reproduce:
Try this case-specific repro: https://github.com/baal2000/RoslynatorAnalyzerNRE

[baal2000]

This could be helpful to others who need to troubleshoot other AD0001 warnings.

I could not find if there is a simple cross-platform Roslyn analyzer error logging that a user can take and bring to the developer or to simplify the issue reproduction without having to setup a dev environment.

I realize this maybe still too steep of a learning curve due to some low-level coding effort involved into the troubleshooting. Please comment if there is a simpler technique.

So I placed

try
{
        [   InvocationExpressionAnalyzer.AnalyzeInvocationExpression body ]
}
catch (NullReferenceException ex)
{
      Debug.Fail($"{ex.Message}{Environment.NewLine}{ex.StackTrace}");
}

into the particular analyzer mentioned in AD0001 warning. Then compiled in debug and replaced the stock version of the analyzer dll with the custom along with the pdb file.

Running dotnet build gave

/usr/share/dotnet/sdk/6.0.302/Roslyn/Microsoft.CSharp.Core.targets(75,5): error : Process terminated. Assertion failed. [/home/sergepavlov/Repro/RoslynatorAnalyzerNRE/RoslynatorAnalyzerNRE.csproj]
  Microsoft.CSharp.Core.targets(75, 5): Object reference not set to an instance of an object.
  Microsoft.CSharp.Core.targets(75, 5):    at Roslynator.CSharp.Analysis.AvoidBoxingOfValueTypeAnalysis.Analyze(SyntaxNodeAnalysisContext context, SimpleMemberInvocationExpressionInfo& invocationInfo) in /home/sergepavlov/Repro/Analyzers/CSharp/Analysis/AvoidBoxingOfValueTypeAnalysis.cs:line 41
  Microsoft.CSharp.Core.targets(75, 5):    at Roslynator.CSharp.Analysis.InvocationExpressionAnalyzer.AnalyzeInvocationExpression(SyntaxNodeAnalysisContext context) in /home/sergepavlov/Repro/Analyzers/CSharp/Analysis/InvocationExpressionAnalyzer.cs:line 450
  Microsoft.CSharp.Core.targets(75, 5):    at Roslynator.CSharp.Analysis.InvocationExpressionAnalyzer.AnalyzeInvocationExpression(SyntaxNodeAnalysisContext context) in /home/sergepavlov/Repro/Analyzers/CSharp/Analysis/InvocationExpressionAnalyzer.cs:line 450
  Microsoft.CSharp.Core.targets(75, 5):    at Roslynator.CSharp.Analysis.InvocationExpressionAnalyzer.<>c.<Initialize>b__3_0(SyntaxNodeAnalysisContext f) in /home/sergepavlov/Repro/Analyzers/CSharp/Analysis/InvocationExpressionAnalyzer.cs:line 59
  Microsoft.CSharp.Core.targets(75, 5):    at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.<>c__62`1.<ExecuteSyntaxNodeAction>b__62_0(ValueTuple`2 data)
  Microsoft.CSharp.Core.targets(75, 5):    at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.ExecuteAndCatchIfThrows_NoLock[TArg](DiagnosticAnalyzer analyzer, Action`1 analyze, TArg argument, Nullable`1 info)
  Microsoft.CSharp.Core.targets(75, 5):    at Microsoft.CodeAnalysis.Diagnostics.AnalyzerExecutor.ExecuteAndCatchIfThrows[TArg](DiagnosticAnalyzer analyzer, Action`1 analyze, TArg argument, Nullable`1 info)
...

After that it was a matter of adding another try/catch to the AvoidBoxingOfValueTypeAnalysis.Analyze method in question to find out what code pattern caused the analyzer to fail.

try
{
    if (!expression.IsKind(SyntaxKind.InterpolatedStringExpression, SyntaxKind.AddExpression)
        && parameters[0].Type.IsObject()
        && context.SemanticModel.GetTypeSymbol(expression, context.CancellationToken)
            .IsValueType)
    {
        DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.AvoidBoxingOfValueType, argument);
        return;
    }
}
catch (NullReferenceException)
{
    DiagnosticHelpers.ReportDiagnostic(context, DiagnosticRules.AvoidBoxingOfValueType, argument);
}