adds already sent exception in update message

app/config/errors.php

@@ -785,5 +785,10 @@ return [
         'name' => Exception::MESSAGE_NOT_FOUND,
         'description' => 'Message with the requested ID could not be found.',
         'code' => 404,
+    ],
+    Exception::MESSAGE_ALREADY_SENT => [
+        'name' => Exception::MESSAGE_ALREADY_SENT,
+        'description' => 'Message with the requested ID has already been sent.',
+        'code' => 400,
     ]
 ];

app/controllers/api/messaging.php

@@ -1703,6 +1703,10 @@ App::patch('/v1/messaging/messages/email/:messageId')
             throw new Exception(Exception::MESSAGE_NOT_FOUND);
         }
 
+        if ($message->getAttribute('status') === 'sent') {
+            throw new Exception(Exception::MESSAGE_ALREADY_SENT);
+        }
+
         if (\count($to) > 0) {
             $message->setAttribute('to', $to);
         }

src/Appwrite/Extend/Exception.php

@@ -240,6 +240,7 @@ class Exception extends \Exception
 
     /** Message */
     public const MESSAGE_NOT_FOUND                  = 'message_not_found';
+    public const MESSAGE_ALREADY_SENT               = 'message_already_sent';
 
     protected $type = '';
     protected $errors = [];