Я получаю следующее сообщение об ошибке:
Warning: Environment variable SUMO_HOME is not set, using built in type maps.
Warning: Environment variable SUMO_HOME is not set, schema resolution will use slow website lookups.
Error: unable to open file 'https://sumo.dlr.de/xsd/types_file.xsd'
In file 'built in type map'
At line/column 1/0.
The types could not be loaded from 'built in type map'.
Quitting (on error).
Что может быть причиной этого?