auth: add helper 'throw' method for GUI prompt setting

Author: mjcheetham

src/shared/Core/Authentication/AuthenticationBase.cs

@@ -3,8 +3,6 @@
 using System.Diagnostics;
 using System.IO;
 using System.Linq;
-using System.Reflection;
-using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 
@@ -92,6 +90,16 @@ protected void ThrowIfUserInteractionDisabled()
             }
         }
 
+        protected void ThrowIfGuiPromptsDisabled()
+        {
+            if (!Context.Settings.IsGuiPromptsEnabled)
+            {
+                Context.Trace.WriteLine($"{Constants.EnvironmentVariables.GitTerminalPrompts} is 0; GUI prompts have been disabled.");
+
+                throw new InvalidOperationException("Cannot show prompt because GUI prompts have been disabled.");
+            }
+        }
+
         protected void ThrowIfTerminalPromptsDisabled()
         {
             if (!Context.Settings.IsTerminalPromptsEnabled)