This error is getting really annoying on my dev account:

Cannot find function undefined in object

The line this happen is

const lastTaskStatus = taskUtil.getStatus(`customscript_${config.client.id}_pay_bills_mr`);
                if (lastTaskStatus) {
if (lastTaskStatus.stage === task.MapReduceStage.GET_INPUT) {
                            progress = lastTaskStatus.getPercentageCompleted();
                        }
}