PipeReader.AdvanceTo throws InvalidCastException

[AArnott]

I'm puzzled by the fact that PipeReader.AdvanceTo accepts a default(SequencePosition) but throws InvalidCastException when provided a position from an empty sequence. Is that by design?

var pipe = new Pipe();
pipe.Reader.AdvanceTo(default); // this works
pipe.Reader.AdvanceTo(ReadOnlySequence<byte>.Empty.Start); // this throws InvalidCastException

Should it throw ArgumentException instead given the SequencePosition came from an unrelated ReadOnlySequence<byte>?

I'm a bit puzzled that PipeReader.AdvanceTo can be called before reading anyway.

[AArnott]

AdvanceTo(default) throws something reasonable now:

Unhandled exception. System.InvalidOperationException: NoReadingOperationToComplete
   at System.IO.Pipelines.ThrowHelper.ThrowInvalidOperationException_NoReadToComplete()
   at System.IO.Pipelines.Pipe.AdvanceReader(BufferSegment consumedSegment, Int32 consumedIndex, BufferSegment examinedSegment, Int32 examinedIndex)
   at System.IO.Pipelines.Pipe.AdvanceReader(SequencePosition& consumed, SequencePosition& examined)
   at System.IO.Pipelines.Pipe.AdvanceReader(SequencePosition& consumed)
   at System.IO.Pipelines.Pipe.DefaultPipeReader.AdvanceTo(SequencePosition consumed)
   at Program.Main()
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)

But AdvanceTo(ReadOnlySequence<byte>.Empty.Start) still throws badly (in fact, the exception message looks like it is a token that was meant to be replaced):

Unhandled exception. System.InvalidCastException: Arg_InvalidCastException
   at System.IO.Pipelines.Pipe.AdvanceReader(SequencePosition& consumed, SequencePosition& examined)
   at System.IO.Pipelines.Pipe.AdvanceReader(SequencePosition& consumed)
   at System.IO.Pipelines.Pipe.DefaultPipeReader.AdvanceTo(SequencePosition consumed)
   at Program.Main()
   at System.Reflection.MethodBaseInvoker.InterpretedInvoke_Method(Object obj, IntPtr* args)
   at System.Reflection.MethodBaseInvoker.InvokeWithNoArgs(Object obj, BindingFlags invokeAttr)