Make sure the Runspace is available and throw otherwise

Author: daxian-dbw

shell/AIShell.Integration/AIShell.psm1

@@ -7,5 +7,10 @@ if ($null -eq $module -or $module.Version -lt [version]"2.4.2") {
     throw "The PSReadLine v2.4.2-beta2 or higher is required for the AIShell module to work properly."
 }
 
+$runspace = $Host.Runspace
+if ($null -eq $runspace) {
+    throw "Failed to import the module because '`$Host.Runspace' unexpectedly returns null.`nThe host details:`n$($Host | Out-String -Width 120)"
+}
+
 ## Create the channel singleton when loading the module.
-$null = [AIShell.Integration.Channel]::CreateSingleton($host.Runspace, [Microsoft.PowerShell.PSConsoleReadLine])
+$null = [AIShell.Integration.Channel]::CreateSingleton($runspace, [Microsoft.PowerShell.PSConsoleReadLine])

shell/AIShell.Integration/Channel.cs

@@ -31,6 +31,9 @@ public class Channel : IDisposable
 
     private Channel(Runspace runspace, Type psConsoleReadLineType)
     {
+        ArgumentNullException.ThrowIfNull(runspace);
+        ArgumentNullException.ThrowIfNull(psConsoleReadLineType);
+
         _runspace = runspace;
         _psrlType = psConsoleReadLineType;
         _connSetupWaitHandler = new ManualResetEvent(false);