net: Prevent property access throws during close

Fix #3455.

The remoteAddress and remotePort properties are
dynamically retrieved from _getpeername().

While _getpeername() checks if the _handle is
null, it is also possible for the tcp_wrapped
_handle.getpeername() to return null on error.

Such a condition happens when the remote closes
and one of these properties is accessed before
_handle is set to null.