var configurationArray = flow.get("configurationArray") || [];
var configurationId = msg.topic.split("/")[1];
var configuration = {
  configID: this.configurationID,
  configurationModules: this.MSGesture.payload
};

if(!configurationArray.find(x => x.configID == this, configurationId)){
  configurationArray.push(this.configuration);
} else {
  //to do
}

Cannot read property 'configId' of undefined