Fix quotes in exception messages

Author: fabpot

Command/Command.php

@@ -255,7 +255,7 @@ public function run(InputInterface $input, OutputInterface $output)
             $statusCode = $this->execute($input, $output);
 
             if (!\is_int($statusCode)) {
-                throw new \TypeError(sprintf('Return value of "%s::execute()" must be of the type int, %s returned.', static::class, \gettype($statusCode)));
+                throw new \TypeError(sprintf('Return value of "%s::execute()" must be of the type int, "%s" returned.', static::class, \gettype($statusCode)));
             }
         }