I have a problem, hope you can help me solve it

[q913777031]

When I follow the steps, I get the following error.

Error: Value cannot be null. (Parameter 'key')

I have no idea deal with this ,please help me,thanks

[patriksvensson]

@q913777031 Difficult to help you here without a reproducable example. Could you run snich from source and see where the exception is thrown?

[tjrobinson]

I'm also getting this error. It went away when I realised that I had a project with <TargetFrameworks>netcoreapp3.1;net5.0</TargetFrameworks> which had a ProjectReference to a project with <TargetFramework>netcoreapp3.1</TargetFramework>.

Making sure both projects were set to <TargetFrameworks>netcoreapp3.1;net5.0</TargetFrameworks> made the error go away.

Hope that helps?

[SimonCropp]

@patriksvensson would it be helpful to output the stack trace when an unknown exception is hit?

[yooakim]

I also have this error, what can I do to help track it down? the issue happens in this method:

private static string GetNearestFrameworkMoniker(this NuGetFramework framework, IEnumerable<string> candidates)
        {
            var provider = DefaultFrameworkNameProvider.Instance;
            var reducer = new FrameworkReducer();

            var mappings = new Dictionary<NuGetFramework, string>(
                candidates.ToDictionary(
                    x => NuGetFramework.Parse(x, provider), y => y, new NuGetFrameworkFullComparer()));

            return mappings[reducer.GetNearest(framework, mappings.Keys)];
        }

Here's a screenshot from VS2022

[patriksvensson]

@yooakim I would need some kind of minimal reproducible example to be able to fix it.

[yooakim]

@patriksvensson I'll try to spend some time on this over the holidays ;-) Will see what I find.

[VisualBean]

This happens when you dont have the right dotnet installed..
To reproduce
try running snitch with a tfm, that is not installed in your current machine. it produces this error.

[simon-curtis]

The error occurs when there isn't a framework that matches the current target. In my case I was working on a solution that was a net8.0 project that was referencing a net472 lib.

// AnalyzerResultExtensions.cs

namespace Snitch.Analysis
{
    internal static class AnalyzerResultExtensions
    {
+        private static readonly FrameworkReducer FrameworkReducer = new();
+        private static readonly NuGetFrameworkFullComparer NuGetFrameworkFullComparer = new();

        public static string? GetProjectAssetsFilePath(this IAnalyzerResult result)
        {
            return result?.GetProperty("ProjectAssetsFile");
        }
-      public static string GetNearestFrameworkMoniker(this IEnumerable<IAnalyzerResult> source, string framework)
+      public static IAnalyzerResult? GetNearestFrameworkMoniker(this IEnumerable<IAnalyzerResult> source, string framework)
        {
-           var current = NuGetFramework.Parse(framework, DefaultFrameworkNameProvider.Instance);
-           return current.GetNearestFrameworkMoniker(source.Select(x => x.TargetFramework));
+            var nugetFrameworks = source
+                .ToDictionary(
+                    c => NuGetFramework.Parse(c.TargetFramework, DefaultFrameworkNameProvider.Instance),
+                    NuGetFrameworkFullComparer);
+
+            var current = NuGetFramework.Parse(framework, DefaultFrameworkNameProvider.Instance);
+            return FrameworkReducer.GetNearest(current, nugetFrameworks.Keys) is { } nuGetFramework
+                ? nugetFrameworks[nuGetFramework]
+                : null;
        }
-        
-        private static string GetNearestFrameworkMoniker(this NuGetFramework framework, IEnumerable<string> candidates)
-        {
-            var provider = DefaultFrameworkNameProvider.Instance;
-            var reducer = new FrameworkReducer();
-
-            var mappings = new Dictionary<NuGetFramework, string>(
-                candidates.ToDictionary(
-                    x => NuGetFramework.Parse(x, provider), y => y, new NuGetFrameworkFullComparer()));
-
-            return mappings[reducer.GetNearest(framework, mappings.Keys)];
-        }
    }
}

// ProjectBuilder.cs

namespace Snitch.Analysis
{
    internal sealed class ProjectBuilder
    {
        private IAnalyzerResult? Build(AnalyzerManager manager, Project project, string? tfm, int indentation)
        {
            // ...

            var projectAnalyzer = manager.GetProject(project.Path);
            var results = (IEnumerable<IAnalyzerResult>)projectAnalyzer.Build();

            if (!string.IsNullOrWhiteSpace(tfm))
            {
-                var closest = results.GetNearestFrameworkMoniker(tfm);
+                if (results.GetNearestFrameworkMoniker(tfm) is not { } closest)
+                {
+                    throw new Exception(
+                        $"""
+                         Incompaitble frameworks detected!
+                         The framework '{tfm}' is not a valid for the project {project.Name}, possible frameworks:
+                         {string.Join("\n", results.Select(k => $" * {k.TargetFramework}"))}
+                         """);
+                }

                results = results.Where(p => p.TargetFramework.Equals(closest.TargetFramework, StringComparison.OrdinalIgnoreCase));
            }

            return results.FirstOrDefault();
        }
    }
}

Obviously you can change the behaviour to just skip the project if you want, but I think a hard fail is a good error to show to he user.