This PR fixes a zero division error when max_speed = 0. When a way from OSM has max_speed_backward or max_speed_forward equal to zero, we assume that cost or reverse cost must be NULL (it is impossible to have cost without speed; this is a OSM problem and must be fixed in OSM side; it is not a osm2pgrouting problem).
This PR fixes a zero division error when max_speed = 0. When a way from OSM has max_speed_backward or max_speed_forward equal to zero, we assume that cost or reverse cost must be NULL (it is impossible to have cost without speed; this is a OSM problem and must be fixed in OSM side; it is not a osm2pgrouting problem).