Connection: Catch disconnection of a node earlier.

While broadcasting a message, some under disconnecting node can be
reached. This context throws an exception and we try to close this node.
This is wrong because this is too late. This is possible to catch this
exception earlier and avoid the whole disconnection process once again
(which is redundant).

Connection.php

@@ -287,12 +287,21 @@ protected function _run(HoaSocket\Node $node)
                             break;
                         }
 
-                        $this->getListener()->fire(
-                            'message',
-                            new Event\Bucket([
-                                'message' => $frame['message']
-                            ])
-                        );
+                        try {
+                            $this->getListener()->fire(
+                                'message',
+                                new Event\Bucket([
+                                    'message' => $frame['message']
+                                ])
+                            );
+                        } catch (HoaException\Group $e) {
+                            $this->getListener()->fire(
+                                'error',
+                                new Event\Bucket([
+                                    'exception' => $e
+                                ])
+                            );
+                        }
 
                         break;
                     } else {