Update close handler to avoid unhandled promise rejections

Author: SimonFrings

src/ProxyConnector.php

@@ -159,6 +159,8 @@ public function connect($uri)
             // either close active connection or cancel pending connection attempt
             $connecting->then(function (ConnectionInterface $stream) {
                 $stream->close();
+            }, function () {
+                // ignore to avoid reporting unhandled rejection
             });
             $connecting->cancel();
         });

tests/ProxyConnectorTest.php

@@ -542,6 +542,9 @@ public function testRejectedConnectionShouldNotCreateGarbageCycles()
         $proxy = new ProxyConnector('proxy.example.com', $this->connector);
 
         $promise = $proxy->connect('google.com:80');
+
+        $promise->then(null, $this->expectCallableOnce()); // avoid reporting unhandled rejection
+
         unset($promise);
 
         $this->assertEquals(0, gc_collect_cycles());