Polish the code.

Signed-off-by: Yury-Fridlyand <yury.fridlyand@improving.com>

csharp/lib/AsyncClient.cs

@@ -66,12 +66,8 @@ private void FailureCallback(ulong index, ErrorType error_type, IntPtr ptr)
     {
         var error = ptr == IntPtr.Zero ? null : Marshal.PtrToStringAnsi(ptr);
         // Work needs to be offloaded from the calling thread, because otherwise we might starve the client's thread pool.
-        _ = Task.Run(() =>
-        {
-            Console.Error.WriteLine($"FailureCallback : {error_type} : {error}");
-            var message = messageContainer.GetMessage((int)index);
-            message.SetException(new Exception($"{error_type} : {error}"));
-        });
+        _ = Task.Run(() => messageContainer.GetMessage((int)index)
+                .SetException(Errors.MakeException(error_type, error)));
     }
 
     ~AsyncClient() => Dispose();
@@ -119,9 +115,21 @@ private void FailureCallback(ulong index, ErrorType error_type, IntPtr ptr)
 
     internal enum ErrorType : uint
     {
+        /// <summary>
+        /// Represented by <see cref="Errors.UnspecifiedException"/> for user
+        /// </summary>
         Unspecified = 0,
+        /// <summary>
+        /// Represented by <see cref="Errors.ExecutionAbortedException"/> for user
+        /// </summary>
         ExecAbort = 1,
+        /// <summary>
+        /// Represented by <see cref="TimeoutException"/> for user
+        /// </summary>
         Timeout = 2,
+        /// <summary>
+        /// Represented by <see cref="Errors.DisconnectedException"/> for user
+        /// </summary>
         Disconnect = 3,
     }
 

csharp/lib/Errors.cs

@@ -0,0 +1,33 @@
+/**
+ * Copyright GLIDE-for-Redis Project Contributors - SPDX Identifier: Apache-2.0
+ */
+
+using static Glide.AsyncClient;
+
+namespace Glide;
+
+public abstract class Errors
+{
+    public sealed class UnspecifiedException : Exception
+    {
+        internal UnspecifiedException(string? message) : base(message) { }
+    }
+
+    public sealed class ExecutionAbortedException : Exception
+    {
+        internal ExecutionAbortedException(string? message) : base(message) { }
+    }
+
+    public sealed class DisconnectedException : Exception
+    {
+        internal DisconnectedException(string? message) : base(message) { }
+    }
+
+    internal static Exception MakeException(ErrorType type, string? message) => type switch
+    {
+        ErrorType.ExecAbort => new ExecutionAbortedException(message),
+        ErrorType.Disconnect => new DisconnectedException(message),
+        ErrorType.Timeout => new TimeoutException(message),
+        _ => new UnspecifiedException(message),
+    };
+}