Fix cache invalidation for conversation preload

Co-authored-by: Fedor Indutny <79877362+indutny-signal@users.noreply.github.com>

ts/state/ducks/conversations.ts

@@ -5635,7 +5635,7 @@ export function reducer(
   if (action.type === MESSAGE_EXPIRED) {
     return maybeUpdateSelectedMessageForDetails(
       { messageId: action.payload.id, targetedMessageForDetails: undefined },
-      state
+      dropPreloadData(state)
     );
   }
 
@@ -5949,20 +5949,21 @@ export function reducer(
   if (action.type === 'MESSAGES_ADDED') {
     const { conversationId, isActive, isJustSent, isNewMessage, messages } =
       action.payload;
-    const { messagesByConversation, messagesLookup } = state;
-
-    const existingConversation = messagesByConversation[conversationId];
-    if (!existingConversation) {
-      return state;
-    }
-
-    let { newest, oldest, oldestUnseen, totalUnseen } =
-      existingConversation.metrics;
 
     if (messages.length < 1) {
       return state;
     }
 
+    const { messagesByConversation, messagesLookup } = state;
+
+    const existingConversation = messagesByConversation[conversationId];
+    if (!existingConversation) {
+      return dropPreloadData(state);
+    }
+
+    let { newest, oldest, oldestUnseen, totalUnseen } =
+      existingConversation.metrics;
+
     const lookup = fromPairs(
       existingConversation.messageIds.map(id => [id, messagesLookup[id]])
     );