Empty errorCallback throw exception

[c01nd01r]

Hi!
I am install dio_retry_fixed, but when interceptor trying to re-send request, package throw exception.
I'll debug the code a little bit and found unknown function Function(ErrorResult err) errorCallback in code of pub.dev package (https://storage.googleapis.com/pub-packages/packages/dio_retry_fixed-0.1.11-beta.tar.gz)
If I correct understand, this function should be replace logger?
Can you add some extra check?
For example:

if (errorCallback != null)
          errorCallback(ErrorResult(err.request.uri.toString(), err.message,
              extra.retries, err.error.toString()));

Thx.