I'm getting the following command response which doesn't set the error label on the top level object as expected:
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.002-0500 "raw" : {
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.002-0500 "shard-rs1/localhost:20003,localhost:20004" : {
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.002-0500 "errorLabels" : [
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.002-0500 "TransientTransactionError"
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.002-0500 ],
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.002-0500 "ok" : 0,
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "errmsg" : "Transaction 1 has been aborted.",
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "code" : 251,
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "codeName" : "NoSuchTransaction"
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 }
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 },
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "code" : 251,
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "codeName" : "NoSuchTransaction",
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "ok" : 0,
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "errmsg" : "",
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "operationTime" : Timestamp(1551909348, 52),
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "$clusterTime" : {
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "clusterTime" : Timestamp(1551909348, 52),
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "signature" : {
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 "keyId" : NumberLong(0)
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 }
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.003-0500 },
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.004-0500 "recoveryToken" : {
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.004-0500 "shardId" : "shard-rs1"
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.004-0500 }
[multi_stmt_txn_passthrough:convert_to_capped] 2019-03-06T16:55:49.004-0500 }