Consider increasing SignalR log level if message size exceeds max

[pranavkm]

In Blazor Server, when a JSInterop response is larger than the SignalR payload size, no information is available by default that indicates the invocation failed. You have to turn up the SignalR logs up to to Debug to see the actual error:

dbug: Microsoft.AspNetCore.SignalR.HubConnectionHandler[2]
      Error when processing requests.
      System.IO.InvalidDataException: The maximum message size of 32768B was exceeded. The message size can be configured in AddHubOptions.

SignalR calls Hub.OnDisconnectedAsync with this exception but Blazor does not do anything with the exception. Perhaps logging the exception with a higher log level would be helpful.

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[dannyBies]

I ran into this issue as well. I would've expected this to be LogLevel.Error. I'd be happy to provide a PR if wanted.

aspnetcore/src/SignalR/server/Core/src/HubConnectionHandlerLog.cs

Lines 16 to 17 in 23b7049

	private static readonly Action<ILogger, Exception?> _errorProcessingRequest =
	LoggerMessage.Define(LogLevel.Debug, new EventId(2, "ErrorProcessingRequest"), "Error when processing requests.");

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