#1 crash on start when loading cached map data

[Dmitriy Geels]

If map data was updated/removed, on next start program will crash when loading cached data.

dmig@dmig-desktop:~$ metromap/metromap.py
Traceback (most recent call last):
File "metromap/metromap.py", line 677, in <module>
city_changed(CITY)
File "metromap/metromap.py", line 503, in city_changed
MD = MapDisplay(mdlines, mdstations, mdvectors, station_selected, sh, cachedir = CACHEDIR, debug = DEBUG, pb = Iface, one_button = Iface.one_button)
File "/home/dmig/metromap/modules/MapDisplay.py", line 120, in __init__
minx = min(map(lambda st: min(st['x'] - st['diameter'] / 2 - 5, st['namerect'][0] - 5), self.Stations.values()))
ValueError: min() arg is an empty sequence