Fix chat submission

app/soapbox/features/chats/components/chat_message_list.js

@@ -9,7 +9,10 @@ import emojify from 'soapbox/features/emoji/emoji';
 
 const mapStateToProps = (state, { chatMessageIds }) => ({
   me: state.get('me'),
-  chatMessages: chatMessageIds.map(id => state.getIn(['chat_messages', id])).toList(),
+  chatMessages: chatMessageIds.reduce((acc, curr) => {
+    const chatMessage = state.getIn(['chat_messages', curr]);
+    return chatMessage ? acc.push(chatMessage) : acc;
+  }, ImmutableList()),
 });
 
 export default @connect(mapStateToProps)

app/soapbox/reducers/chat_message_lists.js

@@ -8,7 +8,8 @@ import { Map as ImmutableMap, OrderedSet as ImmutableOrderedSet } from 'immutabl
 const initialState = ImmutableMap();
 
 const updateList = (state, chatId, messageIds) => {
-  const newIds = state.get(chatId, ImmutableOrderedSet()).union(messageIds);
+  const ids = state.get(chatId, ImmutableOrderedSet());
+  const newIds = ids.union(messageIds);
   return state.set(chatId, newIds);
 };
 
@@ -29,7 +30,7 @@ export default function chatMessageLists(state = initialState, action) {
   case CHAT_MESSAGES_FETCH_SUCCESS:
     return updateList(state, action.chatId, action.data.map(chat => chat.id));
   case CHAT_MESSAGE_SEND_SUCCESS:
-    return updateList(state, action.chatId, action.data.id);
+    return updateList(state, action.chatId, [action.data.id]);
   default:
     return state;
   }