Core/Channel: properly notify client about invalid channel names

Closes #16190

src/server/game/Chat/Channels/ChannelMgr.cpp

@@ -16,8 +16,9 @@
  * with this program. If not, see <http://www.gnu.org/licenses/>.
  */
 
-#include "Channel.h"
 #include "ChannelMgr.h"
+#include "Channel.h"
+#include "DBCStores.h"
 #include "Player.h"
 #include "World.h"
 #include "WorldSession.h"

src/server/game/Handlers/ChannelHandler.cpp

@@ -54,11 +54,13 @@ void WorldSession::HandleJoinChannel(WorldPacket& recvPacket)
             return;
     }
 
-    if (channelName.empty())
-        return;
-
-    if (isdigit(channelName[0]))
+    if (channelName.empty() || isdigit(channelName[0]))
+    {
+        WorldPacket data(SMSG_CHANNEL_NOTIFY, 1 + channelName.size());
+        data << uint8(CHAT_INVALID_NAME_NOTICE) << channelName;
+        SendPacket(&data);
         return;
+    }
 
     if (ChannelMgr* cMgr = ChannelMgr::forTeam(GetPlayer()->GetTeam()))
         if (Channel* channel = cMgr->GetJoinChannel(channelId, channelName, zone))