[tcp] Ignore exceptions in reader thread if writer was terminated

If we do not ignore the exception, then users may receive an exception
via connectionClosedOnError() on connection termination. Those
exceptions are typically unwanted if they are caused e.g. because the
server does not send a closing stream tag.

We previously ignored exceptions in this case already, but that
behavior was changed with [1: 57961a8cc1]. This commit re-adds the
behavior.

1: 57961a8cc1
   Remove SynchronizationPoint

smack-tcp/src/main/java/org/jivesoftware/smack/tcp/XMPPTCPConnection.java

@@ -1141,16 +1141,26 @@ public class XMPPTCPConnection extends AbstractXMPPConnection {
                 }
             }
             catch (Exception e) {
-                // The exception can be ignored if the the connection is 'done'
-                // or if the it was caused because the socket got closed.
-                if (!done) {
                 // Set running to false since this thread will exit here and notifyConnectionError() will wait until
                 // the reader and writer thread's 'running' value is false.
                 running = false;
-                    // Close the connection and notify connection listeners of the
+
-                    // error.
+                String ignoreReasonThread = null;
-                    notifyConnectionError(e);
+
+                boolean writerThreadWasShutDown = packetWriter.queue.isShutdown();
+                if (writerThreadWasShutDown) {
+                    ignoreReasonThread = "writer";
+                } else if (done) {
+                    ignoreReasonThread = "reader";
                 }
+
+                if (ignoreReasonThread != null) {
+                    LOGGER.log(Level.FINER, "Ignoring " + e + " as " + ignoreReasonThread + " was already shut down");
+                    return;
+                }
+
+                // Close the connection and notify connection listeners of the error.
+                notifyConnectionError(e);
             }
         }
     }