Specific exception type to indicate start failures?

The sample code for handling start failures employs a `catch`-all block. Is it safe to assume that any exception thrown by `StartAsync` indicates that retrying the start operation is appropriate?

I'd feel more comfortable catching a specific exception type that's documented as indicating that a retry is appropriate. I understand that, internally, a variety of exception types may be thrown. But perhaps `StartAsync` should catch those exceptions and wrap them in a single exception type before rethrowing them.

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* ID: c9bc1072-be2c-94f6-49bf-daa9e97dff2d
* Version Independent ID: 36052173-7061-6d01-8aed-915685cd7cf6
* Content: [ASP.NET Core SignalR .NET Client](https://docs.microsoft.com/en-us/aspnet/core/signalr/dotnet-client?view=aspnetcore-3.1&tabs=visual-studio#call-hub-methods-from-client)
* Content Source: [aspnetcore/signalr/dotnet-client.md](https://github.com/aspnet/AspNetCore.Docs/blob/master/aspnetcore/signalr/dotnet-client.md)
* Product: **aspnet-core**
* Technology: **aspnetcore-signalr**
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* Microsoft Alias: **bradyg**