when parse the file 'ietf-subscribed-notifications@2019-09-09.yang' with yang-js, there is 'unable to locate' error

[wubo02093104]

Error [ExpressionError]: [module(ietf-subscribed-notifications)/grouping(subscription-policy-dynamic)/uses(subscription-policy-modifiable)/augment(target/stream)] unable to locate 'target/stream'

[wubo02093104]

other error report when parse the file 'ietf-subscribed-notifications@2019-09-09.yang' :
Error [ExpressionError]: [module(ietf-subscribed-notifications)/notification(subscription-started)/uses(subscription-policy)/refine(target/stream/replay-start-time)] unable to locate 'target/stream/replay-start-time'