Add script and instructions to install the latest version of WSL when…

… the machine is in a bad MSIX state (#11500)

triage/config.yml

@@ -90,6 +90,12 @@ rules:
         name: user-visible-error
         capture:
             field3: error
+
+    - logline:
+        provider: Microsoft.Windows.Subsystem.Lxss
+        task: UserVisibleError
+        field3: Wsl/CallMsi/REGDB_E_CLASSNOTREG
+      set: msix-bad-install-state
 
     - logline:
         provider: Microsoft-Windows-Hyper-V-Chipset
@@ -271,3 +277,17 @@ actions:
         condition: msix-install-error
         debug_message: 'Found evidence of MSIX install error: $error, adding msix tag'
         tag: 'msix'
+
+    - when:
+        condition: msix-bad-install-state
+        user_message: | 
+            Your WSL installation appears to be in a bad state. Can you try running the following command to reinstall WSL (elevated powershell) and see if that solves the issue?
+            
+            ```
+            Invoke-WebRequest -UseBasicParsing "https://raw.githubusercontent.com/microsoft/WSL/master/triage/install-latest-wsl.ps1" -OutFile install-latest-wsl.ps1
+            Set-ExecutionPolicy Bypass -Scope Process -Force
+            .\install-latest-wsl.ps1
+             ```
+            
+            
+        tag: 'msix'

triage/install-latest-wsl.ps1

@@ -0,0 +1,50 @@
+#Requires -RunAsAdministrator
+
+# This script downloads and installs the latest version of the WSL MSI package
+
+$ErrorActionPreference = "Stop"
+Set-StrictMode -Version Latest
+
+$release = Invoke-WebRequest 'https://api.github.com/repos/microsoft/WSL/releases/latest' | ConvertFrom-Json
+$systeminfo = & systeminfo | findstr /C:"System Type"
+if ($systeminfo.contains('x64'))
+{
+    $target = '.x64.msi'
+} elseif ($systeminfo.contains('arm64'))
+{
+    $target = '.arm64.msi'
+} else
+{
+    throw 'Failed to determine system type ($systeminfo)'
+}
+
+[array]$assets = $release.assets | Where-Object { $_.name.ToLower().endswith('.x64.msi')}
+if ($assets.count -ne 1)
+{
+    throw 'Failed to find asset ($assets)'
+}
+
+$target = "$env:tmp\$($assets.name)"
+Write-Host "Downloading $($assets.name) to $target"
+
+$headers = New-Object "System.Collections.Generic.Dictionary[[String],[String]]"
+$headers.Add('Accept','application/octet-stream')
+
+Invoke-WebRequest $assets.url -Out $target -Headers $headers
+
+$MSIArguments = @(
+    "/i"
+    $target
+    "/qn"
+    "/norestart"
+)
+
+$exitCode = (Start-Process -Wait "msiexec.exe" -ArgumentList $MSIArguments -NoNewWindow -PassThru).ExitCode
+if ($exitCode -Ne 0)
+{
+    throw "Failed to install package: $exitCode"
+}
+
+Write-Host 'Installation complete'
+
+Remove-Item $target -Force