user: any;
chatMessages: FirebaseListObservable;
chatMessage: ChatMessage;
userName: Observable;
construct
Check your types buddy, you are assigning the query result in different type of firebase datatype this is not going to work debug your code with correct data types and check on Google if there is changes are made to this code due to a version change. Due to consistently changing of versions in Web development technologies this kind of issue is common. Good luck