Workaround for empty server messages (typing indicator)

kordophone-db/src/repository.rs

@@ -250,6 +250,10 @@ impl<'a> Repository<'a> {
                 Ok(())
             })?;
 
+        // TODO: May need to update conversation metadata here, but this has a perf impact.
+        // Ideally we would consolidate this in the code above, assuming we're only inserting *new* messages, but 
+        // this may not necessarily be the case.
+
         Ok(())
     }
 
@@ -325,8 +329,15 @@ impl<'a> Repository<'a> {
                     conversation_guid,
                     last_message
                 );
-                conversation.date = last_message.date;
-                conversation.last_message_preview = Some(last_message.text.clone());
+
+                if last_message.date > conversation.date {
+                    conversation.date = last_message.date;
+                }
+
+                if !last_message.text.is_empty() && !last_message.text.trim().is_empty() {
+                    conversation.last_message_preview = Some(last_message.text.clone());
+                }
+
                 self.insert_conversation(conversation)?;
             }
         }