[quote] Crappy chat quote implementation.

modules/ChatQuotes/Json/NullToEmptyObjectResolver.cs

@@ -0,0 +1,18 @@
+using Newtonsoft.Json;
+using Newtonsoft.Json.Serialization;
+
+namespace West.TelegramBot.ChatQuotes.Json
+{
+    class NullToEmptyObjectResolver : DefaultContractResolver
+    {
+        protected override IList<JsonProperty> CreateProperties(Type type, MemberSerialization memberSerialization)
+        {
+            return type.GetProperties()
+                .Select(p => {
+                    var jp = base.CreateProperty(p, memberSerialization);
+                    jp.ValueProvider = new NullToEmptyStringValueProvider(p);
+                    return jp;
+                }).ToList();
+        }
+    }
+}

modules/ChatQuotes/Json/NullToEmptyObjectValueProvider.cs

@@ -0,0 +1,26 @@
+using System.Reflection;
+using Newtonsoft.Json.Serialization;
+using Telegram.Bot.Types;
+
+namespace West.TelegramBot.ChatQuotes.Json;
+
+public class NullToEmptyStringValueProvider : IValueProvider
+{
+    private readonly PropertyInfo _memberInfo;
+    public NullToEmptyStringValueProvider(PropertyInfo memberInfo)
+    {
+        _memberInfo = memberInfo;
+    }
+
+    public object? GetValue(object target)
+    {
+        var result = _memberInfo.GetValue(target);
+        if (_memberInfo.PropertyType == typeof(Message) && result == null) result = new object();
+        return result;
+    }
+
+    public void SetValue(object target, object value)
+    {
+        _memberInfo.SetValue(target, value);
+    }
+}