[FIX] Reactions may present empty names of who reacted when using Rea…

…l Names (#17536)

app/utils/server/lib/normalizeMessagesForUser.js

@@ -11,6 +11,10 @@ const filterStarred = (message, uid) => {
 
 // TODO: we should let clients get user names on demand instead of doing this
 
+function getNameOfUsername(users, username) {
+	return users.get(username) || username;
+}
+
 export const normalizeMessagesForUser = (messages, uid) => {
 	// if not using real names, there is nothing else to do
 	if (!settings.get('UI_Use_Real_Name')) {
@@ -33,28 +37,27 @@ export const normalizeMessagesForUser = (messages, uid) => {
 			.forEach((reaction) => reaction.usernames.forEach((username) => usernames.add(username)));
 	});
 
-	const users = {};
+	const names = new Map();
 
 	Users.findUsersByUsernames([...usernames.values()], {
 		fields: {
 			username: 1,
 			name: 1,
 		},
 	}).forEach((user) => {
-		users[user.username] = user.name;
+		names.set(user.username, user.name);
 	});
 
 	messages.forEach((message) => {
 		if (!message.u) {
 			return;
 		}
-		message.u.name = users[message.u.username];
+		message.u.name = getNameOfUsername(names, message.u.username);
 
-		(message.mentions || []).forEach((mention) => { mention.name = users[mention.username]; });
+		(message.mentions || []).forEach((mention) => { mention.name = getNameOfUsername(names, mention.username); });
 
 		Object.keys(message.reactions || {}).forEach((reaction) => {
-			const names = message.reactions[reaction].usernames.map((username) => users[username]);
-			message.reactions[reaction].names = names;
+			message.reactions[reaction].names = message.reactions[reaction].usernames.map((username) => getNameOfUsername(names, username));
 		});
 	});