Catch RemoteRpcException, refactor Session.InvokeRpcAsync, remove unused using

Co-authored-by: SteveSandersonMS <1101362+SteveSandersonMS@users.noreply.github.com>

Author: Copilot

dotnet/src/Client.cs

@@ -590,13 +590,13 @@ public async Task<List<SessionMetadata>> ListSessionsAsync(CancellationToken can
         return response.Sessions;
     }
 
-    private static async Task<T> InvokeRpcAsync<T>(JsonRpc rpc, string method, object?[]? args, CancellationToken cancellationToken)
+    internal static async Task<T> InvokeRpcAsync<T>(JsonRpc rpc, string method, object?[]? args, CancellationToken cancellationToken)
     {
         try
         {
             return await rpc.InvokeWithCancellationAsync<T>(method, args, cancellationToken);
         }
-        catch (StreamJsonRpc.RemoteInvocationException ex)
+        catch (StreamJsonRpc.RemoteRpcException ex)
         {
             throw new IOException($"Communication error with Copilot CLI: {ex.Message}", ex);
         }

dotnet/src/Session.cs

@@ -80,17 +80,8 @@ internal CopilotSession(string sessionId, JsonRpc rpc, string? workspacePath = n
         WorkspacePath = workspacePath;
     }
 
-    private async Task<T> InvokeRpcAsync<T>(string method, object?[]? args, CancellationToken cancellationToken)
-    {
-        try
-        {
-            return await _rpc.InvokeWithCancellationAsync<T>(method, args, cancellationToken);
-        }
-        catch (StreamJsonRpc.RemoteInvocationException ex)
-        {
-            throw new IOException($"Communication error with Copilot CLI: {ex.Message}", ex);
-        }
-    }
+    private Task<T> InvokeRpcAsync<T>(string method, object?[]? args, CancellationToken cancellationToken) =>
+        CopilotClient.InvokeRpcAsync<T>(_rpc, method, args, cancellationToken);
 
     /// <summary>
     /// Sends a message to the Copilot session and waits for the response.

dotnet/src/Types.cs

@@ -2,7 +2,6 @@
  *  Copyright (c) Microsoft Corporation. All rights reserved.
  *--------------------------------------------------------------------------------------------*/
 
-using System.IO;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using Microsoft.Extensions.AI;