Thumbor: AttributeError: REDIS_STORAGE_IGNORE_ERRORS when using smart

[macrozone]

i tried the thumbor chart. While the it works good for resizing, i get an error when using /smart in the route. The thumbor pod then logs:

    focal_points = yield gen.maybe_future(self.context.modules.storage.get_detector_data(self.smart_storage_key))
  File "/usr/local/lib/python2.7/site-packages/tornado/gen.py", line 1055, in run
    value = future.result()
  File "/usr/local/lib/python2.7/site-packages/tornado/concurrent.py", line 238, in result
    raise_exc_info(self._exc_info)
  File "/usr/local/lib/python2.7/site-packages/tornado/gen.py", line 307, in wrapper
    yielded = next(result)
  File "/usr/local/lib/python2.7/site-packages/thumbor/storages/mixed_storage.py", line 74, in get_detector_data
    result = yield gen.maybe_future(self.detector_storage.get_detector_data(path))
  File "/usr/local/lib/python2.7/site-packages/tornado/concurrent.py", line 483, in wrapper
    future.result()
  File "/usr/local/lib/python2.7/site-packages/tornado/concurrent.py", line 238, in result
    raise_exc_info(self._exc_info)
  File "/usr/local/lib/python2.7/site-packages/tornado/concurrent.py", line 471, in wrapper
    result = f(*args, **kwargs)
  File "/usr/local/lib/python2.7/site-packages/tc_redis/storages/redis_storage.py", line 129, in get_detector_data
    callback(self._get_detector_data(path))
  File "/usr/local/lib/python2.7/site-packages/tc_redis/utils.py", line 23, in wrapper
    exc_value
  File "/usr/local/lib/python2.7/site-packages/tc_redis/storages/redis_storage.py", line 69, in on_redis_error
    if self.context.config.REDIS_STORAGE_IGNORE_ERRORS is True:
  File "/usr/local/lib/python2.7/site-packages/derpconf/config.py", line 211, in __getattr__
    raise AttributeError(name)
AttributeError: REDIS_STORAGE_IGNORE_ERRORS

it seems like REDIS_STORAGE_IGNORE_ERRORS is not defined (?)