Regression: Edit messages after opening thread (#18375)

app/threads/client/flextab/thread.js

@@ -275,9 +275,15 @@ Template.thread.onCreated(async function() {
 });
 
 Template.thread.onDestroyed(function() {
-	const { Threads, threadsObserve, callbackRemove } = this;
+	const { Threads, threadsObserve, callbackRemove, state } = this;
 	Threads.remove({});
 	threadsObserve && threadsObserve.stop();
 
 	callbackRemove && callbackRemove();
+
+	const tmid = state.get('tmid');
+	const rid = state.get('rid');
+	if (rid && tmid) {
+		delete chatMessages[`${ rid }-${ tmid }`];
+	}
 });