Fix NPE when channel is closed after being fetched from pool, close AsyncHttpClient#1402

Motivation:

channel.remoteAddress() returns null if channel was closed after it was
pulled from the pool, causing a NPE.

Modification:

Only schedule timeout when channel’s remoteAddress is not null

Result:

No more NPE

Author: slandelle

client/src/main/java/org/asynchttpclient/netty/request/NettyRequestSender.java

@@ -38,6 +38,7 @@
 
 import java.io.IOException;
 import java.net.InetSocketAddress;
+import java.net.SocketAddress;
 import java.util.List;
 
 import org.asynchttpclient.AsyncHandler;
@@ -234,7 +235,12 @@ private <T> ListenableFuture<T> sendRequestWithOpenChannel(Request request, Prox
             }
         }
 
-        scheduleRequestTimeout(future, (InetSocketAddress) channel.remoteAddress());
+        SocketAddress channelRemoteAddress = channel.remoteAddress();
+        if (channelRemoteAddress != null) {
+            // otherwise, bad luck, the channel was closed, see bellow
+            scheduleRequestTimeout(future, (InetSocketAddress) channelRemoteAddress);
+        }
+
         future.setChannelState(ChannelState.POOLED);
         future.attachChannel(channel, false);