Fix memory leak

Author: Johann Saunier

src/Consumer.php

@@ -63,6 +63,8 @@ public function __construct(AMQPQueue $queue, LoopInterface $loop, $interval, $m
         $this->loop = $loop;
         $this->max = $max;
         $this->timer = $this->loop->addPeriodicTimer($interval, $this);
+
+        $this->on('close_amqp_consumer', [$this, 'close']);
     }
 
     /**
@@ -75,15 +77,14 @@ public function __invoke()
         if ($this->closed) {
             throw new BadMethodCallException('This consumer object is closed and cannot receive any more messages.');
         }
+
         $counter = 0;
         while ($envelope = $this->queue->get()) {
             $this->emit('consume', [$envelope, $this->queue]);
             if ($this->max && ++$counter >= $this->max) {
                 return;
             }
         }
-
-        $this->on('close_amqp_consumer', [$this, 'close']);
     }
 
     /**