compilation broken due to depency: empy 4.0 python module

[mikkab]

empy version 3.3.4 works fine, empy 4.0 show:
Caught exception! 'dict' object has no attribute 'unknownScriptName'

[sorki]

Empy is used here https://github.com/dronecan/dronecan_dsdlc/blob/master/dronecan_dsdlc.py#L107 so maybe move the issue there but it seem most of the ecosystem (even ROS) just pins empy to 3.3.4 as the latest version causes a lot of breakage and the reason is not quite obvious.