AutoPkg 1.3 is incompatible with JSSImporter. UPDATE: fixed in version 1.3.1
AutoPkg 1.3 was released this week and unfortunately, changes that were made to the reading of the configuration file breaks JSSImporter. Therefore, running AutoPkg recipes while JSSImporter is installed and configured will fail. It is advised not to upgrade at this time.
If you already upgraded and encountered the problem, the workaround is to revert to AutoPkg 1.2. A downgrade should be possible simply by installing the package.
UPDATE 2019-11-06
The problem has been fixed in version 1.3.1 of AutoPkg, which was released today.