refactor: Add return statement.

Signed-off-by: Pol Dellaiera <pol.dellaiera@protonmail.com>

src/Operation/Tails.php

@@ -41,7 +41,7 @@ static function (Iterator $iterator): Generator {
                     array_shift($data);
                 }
 
-                yield [];
+                return yield [];
             };
     }
 }