When initializing the BulkWriteError, the document set is not the correct one, the first document of the batch is used instead, it should used the document in the batch at the index returned by the WriteError (https://github.com/mongodb/mongo-go-driver/blob/b414b897457665f12997cefd10ad934ccb9dfb3e/mongo/errors.go#L129)

https://github.com/mongodb/mongo-go-driver/blob/b414b897457665f12997cefd10ad934ccb9dfb3e/mongo/bulk_write.go#L156