♻️ refactor(message): improve subject logging with early returns

- use early returns and `else` blocks for better readability and reduced nesting
- add a log message to indicate emails with no subject

src/message.rs

@@ -163,9 +163,12 @@ impl Message {
     }
 
     async fn log_message_subjects(&self, list: &ListMessagesResponse) -> Result<(), Error> {
-        if let Some(messages) = &list.messages {
+        let Some(messages) = &list.messages else {
+            return Ok(());
+        };
+
         for message in messages {
-                if let Some(id) = &message.id {
+            let Some(id) = &message.id else { continue };
             log::trace!("{id}");
             let (_res, m) = self
                 .hub
@@ -179,8 +182,11 @@ impl Message {
                 .map_err(Box::new)?;
 
             let mut subject = String::new();
-                    if let Some(payload) = m.payload {
-                        if let Some(headers) = payload.headers {
+            let Some(payload) = m.payload else { continue };
+            let Some(headers) = payload.headers else {
+                continue;
+            };
+
             for header in headers {
                 if header.name.is_some()
                     && header.name.unwrap() == "Subject"
@@ -192,13 +198,13 @@ impl Message {
                     continue;
                 }
             }
-                        }
-                    }
 
+            if subject.is_empty() {
+                log::info!("***Email with no subject***");
+            } else {
                 log::info!("{subject:?}");
             }
         }
-        }
 
         Ok(())
     }