Documentation for Query talks about using run() to get errors, but it's not in the example

from stem.descriptor.remote import Query

query = Query(
  '/tor/server/all',
  block = True,
  timeout = 30,
)

print('Current relays:')

if not query.error:
  for desc in query:
    print(desc.fingerprint)
else:
  print('Unable to retrieve the server descriptors: %s' % query.error)