dotnet-counters: default IncrementingEventCounter values crashes the ConsoleMonitor

[dorki]

When creating IncrementingEventCounter (https://github.com/dotnet/corefx/blob/61a6264018989e06d314b68d57bd91b4b72e4360/src/Common/src/CoreLib/System/Diagnostics/Tracing/IncrementingEventCounter.cs) without setting the DisplayRateTimeScale property, the property value will remain the default TimeSpan.Zero.

While dumping the value to the EventSource using the DiagnosticCounter.WritePayload method, this will be converted into string.Emtpy:
payload.DisplayRateTimeScale = (DisplayRateTimeScale == TimeSpan.Zero) ? "" : DisplayRateTimeScale.ToString("c")
(https://github.com/dotnet/corefx/blob/61a6264018989e06d314b68d57bd91b4b72e4360/src/Common/src/CoreLib/System/Diagnostics/Tracing/IncrementingEventCounter.cs#L66)

But in the dotnet-counters the IncrementingCounterPayload constructor doesn't handle this case of empty string:

diagnostics/src/Tools/dotnet-counters/CounterPayload.cs

Line 58 in 26d292c

m_DisplayRateTimeScale = TimeSpan.Parse(payloadFields["DisplayRateTimeScale"].ToString()).ToString("%s' sec'");

which will cause a System.FormatException to be thrown

[sywhang]

Thanks for reporting this issue @dorki! This should be fixed with #433 - please feel free to reopen the issue if it persists.