McpServerPrimitiveCollection ArgumentNullException

[kevklam]

Describe the bug
[ArgumentNullException]: Value cannot be null.
Parameter name: comparer
at System.Collections.Concurrent.ConcurrentDictionary2..ctor(Int32 concurrencyLevel, Int32 capacity, Boolean growLockArray, IEqualityComparer1 comparer)
at System.Collections.Concurrent.ConcurrentDictionary2..ctor(IEqualityComparer1 comparer)
at ModelContextProtocol.Server.McpServerPrimitiveCollection1..ctor(IEqualityComparer1 keyComparer)
at ModelContextProtocol.McpServerOptionsSetup.Configure(McpServerOptions options)

This is caused by introduction of default-null IEqualityComparer in McpServerPrimitiveCollection constructor, apparently null is not actually accepted by ConcurrentDictionary constructor despite it being a nullable value.

To Reproduce
Steps to reproduce the behavior:

1. Setup an MCP server with no tools, then McpServerOptionsSetup.Configure() will do this:
   McpServerPrimitiveCollection toolCollection = options.Capabilities?.Tools?.ToolCollection ?? [];

the case where ToolCollection is null results in the above call stack

Expected behavior
Server runs with no tools

Logs
If applicable, add logs to help explain your problem.

Additional context
Add any other context about the problem here.

[stephentoub]

apparently null is not actually accepted by ConcurrentDictionary constructor despite it being a nullable value.

On .NET Framework. This was fixed in .NET Core eight years ago.
dotnet/corefx#18441

[stephentoub]

What version of ModelContextProtocol are you using? And can you share a simple standalone repro?

[stephentoub]

Nevermind, I see this was already fixed by #588. The fix will be included in the next build on nuget, which I expect to be in the next couple of days.

Thanks.