Guard IO service timer thread against accidental null pointer dereference (#1626)
Guard IO service timer thread against accidental null pointer dereference (#1626)

The TCPTransportInterface may segfault on destruction if a transport
instance fails to initialize properly. This is due to the unguarded
access to io_service_timers_thread_.

Signed-off-by: Timo Röhling <98c2d5a1e48c998bd9ba9dbc53d6857beae1c9bd@gaussglocke.de>
eProsima/Fast-RTPS,eProsima/Fast-DDS,eProsima/Fast-RTPS,eProsima/Fast-RTPS,eProsima/Fast-RTPS,eProsima/Fast-RTPS,eProsima/Fast-DDS,eProsima/Fast-DDS,eProsima/Fast-DDS,eProsima/Fast-DDS