Don't dereference the end iterator when async_connect exhausts the range.

asio/include/asio/impl/connect.hpp

diff --git a/asio/include/asio/impl/connect.hpp b/asio/include/asio/impl/connect.hpp
index 471460d..5c8650f 100644
--- a/asio/include/asio/impl/connect.hpp
+++ b/asio/include/asio/impl/connect.hpp
@@ -324,7 +324,8 @@
         }
 
         handler_(static_cast<const asio::error_code&>(ec),
-            static_cast<const typename Protocol::endpoint&>(*iter));
+            static_cast<const typename Protocol::endpoint&>(
+              ec || iter == end ? typename Protocol::endpoint() : *iter));
       }
     }