DurableTask.Analyzers throws ArgumentNullException('node') when orchestrator lambda is inside a foreach loop

[kshyju]

Description

All orchestration analyzers (DateTimeOrchestrationAnalyzer, DelayOrchestrationAnalyzer, ThreadTaskOrchestrationAnalyzer, etc.) throw System.ArgumentNullException with message Value cannot be null. (Parameter 'node') when AddOrchestratorFunc is called with an inline lambda inside a foreach loop that captures a loop-scoped variable.

This affects both Microsoft.DurableTask.Analyzers v0.2.0 and v0.3.0.

Steps to Reproduce

1. Clone the minimal repro: https://github.com/kshyju/DurableTaskAnalyzersBugRepro
2. Run dotnet build

The repro project uses <TreatWarningsAsErrors>true</TreatWarningsAsErrors> so the AD0001 warnings surface as build errors.

Minimal Repro Code

var builder = FunctionsApplication.CreateBuilder(args);

string[] names = ["A", "B"];

builder.ConfigureDurableWorker().AddTasks(tasks =>
{
    foreach (string name in names)
    {
        // This triggers the analyzer bug — the lambda captures `name` from the foreach loop.
        tasks.AddOrchestratorFunc<string, string>(
            name,
            async (ctx, input) =>
            {
                ILogger logger = ctx.CreateReplaySafeLogger(name);
                return await ctx.CallActivityAsync<string>("Activity", input);
            });
    }
});

Note: The same code works fine when the AddOrchestratorFunc call is not inside a foreach loop.

Error Output

CSC : error AD0001: Analyzer 'Microsoft.DurableTask.Analyzers.Functions.Orchestration.CancellationTokenOrchestrationAnalyzer' threw an exception of type 'System.ArgumentNullException' with message 'Value cannot be null. (Parameter 'node')'.
CSC : error AD0001: Analyzer 'Microsoft.DurableTask.Analyzers.Functions.Orchestration.OtherBindingsOrchestrationAnalyzer' threw an exception of type 'System.ArgumentNullException' with message 'Value cannot be null. (Parameter 'node')'.
CSC : error AD0001: Analyzer 'Microsoft.DurableTask.Analyzers.Orchestration.DateTimeOrchestrationAnalyzer' threw an exception of type 'System.ArgumentNullException' with message 'Value cannot be null. (Parameter 'node')'.
CSC : error AD0001: Analyzer 'Microsoft.DurableTask.Analyzers.Orchestration.DelayOrchestrationAnalyzer' threw an exception of type 'System.ArgumentNullException' with message 'Value cannot be null. (Parameter 'node')'.
... (all orchestration analyzers crash)

Additional Context

• The analyzer is pulled transitively via Microsoft.Azure.Functions.Worker.Extensions.DurableTask v1.13.1 → Microsoft.DurableTask.Analyzers v0.2.0
• Adding an explicit reference to Microsoft.DurableTask.Analyzers v0.3.0 does not fix the issue — v0.3.0 has the same bug.
• Workaround: Suppress AD0001 in the project file: <NoWarn>$(NoWarn);AD0001</NoWarn>

Environment

• .NET SDK: 8.0 / 9.0 / 10.0
• Microsoft.Azure.Functions.Worker.Extensions.DurableTask: 1.13.1
• Microsoft.DurableTask.Analyzers: 0.2.0 (also repros on 0.3.0)