ArgumentOutOfRangeException - 2.1.0-beta1 #1599

PS version: 7.0.1
PSReadline version: 2.1.0-beta1
os: 10.0.18362.1 (WinBuild.160101.0800)
PS file version: 7.0.1.0
HostName: ConsoleHost (Windows Terminal)
BufferWidth: 120
BufferHeight: 50

 \ s r Tab Backspace Backspace Backspace Backspace Backspace Spacebar . \ s r j Tab Backspace Tab RightArrow Enter
 n p m Spacebar r u n Spacebar s t a r t Enter
 c d Spacebar . . \ . . Enter
 c d Spacebar . . \ . . Backspace Backspace Backspace Backspace Backspace Backspace Backspace Backspace Backspace . UpArrow Enter
 c d s Backspace Spacebar . \ RightArrow Enter
 n p m Spacebar r u n Spacebar RightArrow Enter
 c d Spacebar . . \ . . Enter
 Enter
 . UpArrow Enter
 c d Spacebar . \ s r Tab RightArrow Enter
 n p m RightArrow Enter
 c d Spacebar . . RightArrow Enter
 . \ RightArrow Enter
 c d Spacebar s r Tab RightArrow Enter
 n p m Spacebar r u n Spacebar RightArrow Enter
 c d Spacebar . . Enter
 . Backspace c d Spacebar . . Enter
 . \ RightArrow Enter
 c d Spacebar . . Backspace Backspace . \ s r RightArrow Enter
 n p RightArrow Enter
 c d Spacebar . . Enter
 . . Enter
 c d Spacebar . . Enter
 UpArrow UpArrow UpArrow UpArrow Backspace Backspace Ctrl+Backspace Backspace Enter
 UpArrow Escape

System.ArgumentOutOfRangeException: Index was out of range. Must be non-negative and less than the size of the collection. (Parameter 'index')
   at System.Text.StringBuilder.Insert(Int32 index, String value)
   at Microsoft.PowerShell.PSConsoleReadLine.EditItemDelete.Undo()
   at Microsoft.PowerShell.PSConsoleReadLine.RevertLine(Nullable`1 key, Object arg)
   at Microsoft.PowerShell.PSConsoleReadLine.ProcessOneKey(PSKeyInfo key, Dictionary`2 dispatchTable, Boolean ignoreIfNoAction, Object arg)
   at Microsoft.PowerShell.PSConsoleReadLine.InputLoop()
   at Microsoft.PowerShell.PSConsoleReadLine.ReadLine(Runspace runspace, EngineIntrinsics engineIntrinsics, CancellationToken cancellationToken)