fix: Message type (#1876)

* Fix message type

* Remove type from system entity

src/Discord.Net.Core/Entities/Messages/IMessage.cs

@@ -10,7 +10,7 @@ namespace Discord
     public interface IMessage : ISnowflakeEntity, IDeletable
     {
         /// <summary>
-        ///     Gets the type of this system message.
+        ///     Gets the type of this message.
         /// </summary>
         MessageType Type { get; }
         /// <summary>

src/Discord.Net.WebSocket/Entities/Messages/SocketMessage.cs

@@ -61,6 +61,9 @@ namespace Discord.WebSocket
         /// <inheritdoc />
         public MessageFlags? Flags { get; private set; }
 
+        /// <inheritdoc/>
+        public MessageType Type { get; private set; }
+
         /// <summary>
         ///     Returns all attachments included in this message.
         /// </summary>
@@ -122,6 +125,8 @@ namespace Discord.WebSocket
         }
         internal virtual void Update(ClientState state, Model model)
         {
+            Type = model.Type;
+
             if (model.Timestamp.IsSpecified)
                 _timestampTicks = model.Timestamp.Value.UtcTicks;
 
@@ -185,8 +190,6 @@ namespace Discord.WebSocket
         /// <inheritdoc />
         IMessageChannel IMessage.Channel => Channel;
         /// <inheritdoc />
-        MessageType IMessage.Type => MessageType.Default;
-        /// <inheritdoc />
         IReadOnlyCollection<IAttachment> IMessage.Attachments => Attachments;
         /// <inheritdoc />
         IReadOnlyCollection<IEmbed> IMessage.Embeds => Embeds;

src/Discord.Net.WebSocket/Entities/Messages/SocketSystemMessage.cs

@@ -9,9 +9,6 @@ namespace Discord.WebSocket
     [DebuggerDisplay(@"{DebuggerDisplay,nq}")]
     public class SocketSystemMessage : SocketMessage, ISystemMessage
     {
-        /// <inheritdoc />
-        public MessageType Type { get; private set; }
-
         internal SocketSystemMessage(DiscordSocketClient discord, ulong id, ISocketMessageChannel channel, SocketUser author)
             : base(discord, id, channel, author, MessageSource.System)
         {
@@ -25,8 +22,6 @@ namespace Discord.WebSocket
         internal override void Update(ClientState state, Model model)
         {
             base.Update(state, model);
-
-            Type = model.Type;
         }
         
         private string DebuggerDisplay => $"{Author}: {Content} ({Id}, {Type})";