Product start integration with 3DS. On sandbox account on success call verifyCard logs errors in browser console.
Base.S3Writer: s3 client not initialized
n.cerror @ jsnlog.js?f56f:567
n.sendLogItemsConsole @ jsnlog.js?f56f:630
i.sendBatch @ jsnlog.js?f56f:445
i.log @ jsnlog.js?f56f:425
t.log @ jsnlog.js?f56f:737
t.error @ jsnlog.js?f56f:748
logRouter @ logger.js?1a6e:37
h @ lodash.custom.js?189e:32
capture @ s3Writer.js?12ef:96
capture @ endpointMonitor.js?140f:87
receiveMessage @ 10.9a1cc817eb1b1f693268.songbird.js:1
(anonymous) @ htmlUtility.js?257b:40

Used for integration:
braintree-web/dist/browser/client
braintree-web/dist/browser/hosted-fields
braintree-web/dist/browser/three-d-secure
braintree-web/dist/browser/data-collector
But system continue to works without issues (maybe it is just debug logs).
Thanks, we're aware of the console error (was reported in the Drop-in repo, which uses this as the underlying sdk https://github.com/braintree/braintree-web-drop-in/issues/558)
We've escalated it to Cardinal (our 3DS partner) and are waiting to hear back.
Since the resolution relies on them updating their javascript file, and not anything in this sdk, I'm going to close this issue.