Fix crash in next departures service with journey containing a junction as last leg
example of URL (with a TPC db) /admin?SERVICE=tdg&output_format=&roid=11540478340104307&date=2019-01-22%2013:05
example of URL (with a TPC db) /admin?SERVICE=tdg&output_format=&roid=11540478340104307&date=2019-01-22%2013:05