Using one of the cfg file from darknet repo. (darknet-19 for classification not detection).

https://github.com/AlexeyAB/darknet/blob/master/cfg/darknet19.cfg

opencv/modules/dnn/src/darknet/darknet_io.cpp:678: error: (-212:Parsing error) Unknown layer type: sse in function 'ReadDarknetFromCfgStream'

Seems to be in cost layer...

[cost]
type=sse