Fix "handle is invalid" error on AppVeyor

src/Microsoft.PowerShell.Linux.Host/host.cs

@@ -16,6 +16,7 @@ namespace Microsoft.PowerShell.Linux.Host
         public MyHost(Listener Listener)
         {
             this.Listener = Listener;
+            this.myHostUserInterface = new MyHostUserInterface(Listener.HasUI);
         }
 
         /// <summary>
@@ -44,7 +45,7 @@ namespace Microsoft.PowerShell.Linux.Host
         /// A reference to the implementation of the PSHostUserInterface
         /// class for this application.
         /// </summary>
-        private MyHostUserInterface myHostUserInterface = new MyHostUserInterface();
+        private MyHostUserInterface myHostUserInterface;
 
         /// <summary>
         /// A reference to the runspace used to start an interactive session.

src/Microsoft.PowerShell.Linux.Host/main.cs

@@ -187,8 +187,15 @@ OPTIONS
             set { this.exitCode = value; }
         }
 
+        /// <summary>
+        /// Gets or sets a value indicating whether UI should exit.
+        /// </summary>
+        public bool HasUI;
+
         public Listener(string initialScript, bool loadProfiles)
         {
+            HasUI = (initialScript == null) ? true : false;
+
             // Create the host and runspace instances for this interpreter.
             // Note that this application does not support console files so
             // only the default snap-ins will be available.

src/Microsoft.PowerShell.Linux.Host/ui.cs

@@ -17,10 +17,18 @@ namespace Microsoft.PowerShell.Linux.Host
     /// </summary>
     internal class MyHostUserInterface : PSHostUserInterface, IHostUISupportsMultipleChoiceSelection
     {
+        /// <summary>
+        /// Public constructor
+        /// </summary>
+        public MyHostUserInterface(bool hasUI)
+        {
+            myRawUi = (hasUI) ? new MyRawUserInterface() : null;
+        }
+
         /// <summary>
         /// A reference to the PSRawUserInterface implementation.
         /// </summary>
-        private MyRawUserInterface myRawUi = new MyRawUserInterface();
+        private MyRawUserInterface myRawUi;
 
         /// <summary>
         /// Gets an instance of the PSRawUserInterface class for this host