Place a try catch block in the socket example.

As for issue #1963 it seems that without the try-catch the loop can crash
the server if the client does wait (sleep) or do something strange with the
incoming data.
Seems to me a flushing problem.

Tested on moar 2018.04.

doc/Type/IO/Socket/INET.pod6

@@ -18,10 +18,17 @@ my $listen = IO::Socket::INET.new( :listen,
                                    :localport(3333) );
 loop {
     my $conn = $listen.accept;
-    while my $buf = $conn.recv(:bin) {
-        $conn.write: $buf;
+    try {
+        while my $buf = $conn.recv(:bin) {
+            $conn.write: $buf;
+        }
     }
     $conn.close;
+
+    CATCH {
+          default { .payload.say;      }
+    }
+
 }
 =end code