Fixing exception when migrating tracker from 0.11 to 0.12/0.13 version
Fixing exception when migrating tracker from 0.11 to 0.12/0.13 version

RasaHQ/rasa_core,RasaHQ/rasa_nlu,RasaHQ/rasa_core,RasaHQ/rasa_nlu,RasaHQ/rasa_core,RasaHQ/rasa_nlu