fix: do not send email if 0 notifications

src/lib/mail.ts

@@ -59,7 +59,9 @@ async function consumeQueue() {
           body += `<h3>${message.subject}</h3>\n`
           body += `<div>${message.body}</div>\n`
         }
-        await sendEmail(subject, body, cc || undefined)
+        if (messages.length) {
+          await sendEmail(subject, body, cc || undefined)
+        }
       }
     } else {
       const mail = queue.shift() as MailContent