Check whether there are relations before invoking network analysis module. Fixes #282
Check whether there are relations before invoking network analysis module. Fixes #282

There is an unusual scenario where the current fix is too naive, see issue #80 for further details. At least now we avoid the 500 error in the server and Python crashing badly.

civio/onodo,civio/onodo,civio/onodo,civio/onodo