enhance: show inner exception message if possible when check update failed

Signed-off-by: leo <longshuang@msn.cn>

src/Models/SelfUpdate.cs

@@ -0,0 +1,56 @@
+using System;
+using System.Reflection;
+using System.Text.Json.Serialization;
+
+namespace SourceGit.Models
+{
+    public class Version
+    {
+        [JsonPropertyName("name")]
+        public string Name { get; set; }
+
+        [JsonPropertyName("tag_name")]
+        public string TagName { get; set; }
+
+        [JsonPropertyName("body")]
+        public string Body { get; set; }
+
+        public bool IsNewVersion
+        {
+            get
+            {
+                try
+                {
+                    System.Version version = new System.Version(TagName.Substring(1));
+                    System.Version current = Assembly.GetExecutingAssembly().GetName().Version!;
+                    return current.CompareTo(version) < 0;
+                }
+                catch
+                {
+                    return false;
+                }
+            }
+        }
+    }
+
+    public class AlreadyUpToDate
+    {
+    }
+
+    public class SelfUpdateFailed
+    {
+        public string Reason
+        {
+            get;
+            private set;
+        }
+
+        public SelfUpdateFailed(Exception e)
+        {
+            if (e.InnerException is { } inner)
+                Reason = inner.Message;
+            else
+                Reason = e.Message;
+        }
+    }
+}