SystemTextJsonFormatter throws exceptions when ETW logging is enabled

[dibarbet]

I've been working on converting the Roslyn LSP server to STJ in dotnet/roslyn#73207

When validating the changes in VS, I hit a huge number of exception count regressions (thousands in some scenarios), see this internal link. These regressions were not reproducible in my changes locally, nor in the build from the VS insertion, until I either

1. set the env var StreamJsonRpc_TestWithEventSource
2. or ran VS under perfview using the streamjsonrpc ETW provider (F0CFFE53-BCC5-53F5-8873-995568808A3B)

The exception stacks in the RPS run pretty much all look like the following:

It appears as though we're hitting this throw in TryGetArgumentByNameOrIndex -

vs-streamjsonrpc/src/StreamJsonRpc/SystemTextJsonFormatter.cs

Line 532 in f6a3b48

throw new JsonException("Unexpected value kind for arguments: " + (this.JsonArguments?.ValueKind.ToString() ?? "null"));

because the JsonRpcEventSource is calling to get a string representation of the message with name: null and where JsonArguments is JsonValueKind.Object -

vs-streamjsonrpc/src/StreamJsonRpc/JsonRpcEventSource.cs

Line 297 in f6a3b48

if (request.TryGetArgumentByNameOrIndex(null, i, null, out object? value))