Merge pull request #12116 from Tainan404/issue-12093

Fix client crashing with multiple private chats

bigbluebutton-html5/imports/ui/components/components-data/chat-context/context.jsx

@@ -328,6 +328,7 @@ const reducer = (state, action) => {
             timeWindowIds.forEach((timeWindowId)=> {
               const timeWindow = messages[timeWindowId];
               if (timeWindow.messageType === MESSAGE_TYPES.STREAM) {
+                chat.unreadTimeWindows.delete(timeWindowId);
                 delete newState[chatId][group][timeWindowId];
               }
             });