[vi-mode] GotoFirstNonBlankOfLine crashes PSRL when buffer is empty

[springcomp]

Environment

PS version: 7.2.0-daily.20201215
PSReadline version: 2.1.0
os: 10.0.18362.1130 (WinBuild.160101.0800)
PS file version: 7.2.0.0
HostName: ConsoleHost (Windows Terminal)
BufferWidth: 120
BufferHeight: 30

Exception report

Last 24 Keys

 S e t - P S R e a d L i n e O p t i o n RightArrow Enter Escape _

Exception

System.IndexOutOfRangeException: Index was outside the bounds of the array.
   at System.Text.StringBuilder.get_Chars(Int32 index)
   at Microsoft.PowerShell.PSConsoleReadLine.IsVisibleBlank(Int32 newCurrent)
   at Microsoft.PowerShell.PSConsoleReadLine.GetFirstNonBlankOfLogicalLinePos(Int32 current)
   at Microsoft.PowerShell.PSConsoleReadLine.GotoFirstNonBlankOfLine(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)

Steps to reproduce

Run PSRL:

Set-PSReadLineOption -EditMode Vi

Then type the following sequence: Esc, _

Expected behavior

Nothing should happen. Possibly, key may ding.

Actual behavior

PSRL crashes.

[ghost]

🎉 This issue was addressed in 2051, which has now been successfully released in v2.2.0-beta2. 🎉

[ghost]

🎉 v2.2.0-beta2 has been released which incorporates this pull request. 🎉