https://docs.mongodb.com/manual/reference/program/mongodump/
"--repair is only available for use with mongod instances using the mmapv1 storage engine. You cannot run --repair with mongos or with mongod instances that use the wiredTiger storage engine. To repair data in a mongod instance using wiredTiger use mongod --repair."

I think we should clarify that mongod --repair is the preferred method to recover data after experiencing data corruption regardless of storage engine, and possibly link to https://docs.mongodb.com/manual/tutorial/recover-data-following-unexpected-shutdown/