client.documents.write() fails on an array of documents

I use the following module in debug-write.mjs, to write 2 documents in Documents:

"use strict";

import ml from 'marklogic';

const client = ml.createDatabaseClient({
    host:     'localhost',
    user:     'admin',
    password: 'admin',
    port:     8000,
    authType: 'DIGEST',
});
client.setLogger('debug');

const docs = [
    {content: {hello: 'world'},       uri: '/test/hello.json', contentType: 'application/json'},
    {content: '<hello>world</hello>', uri: '/test/hello.xml',  contentType: 'application/xml'},
];

const res = await client.documents.write(docs).result();
console.dir(res);

I execute it like the following:

➜  time node debug-write.mjs
Debug: challenge request for /v1/ping
Debug: response with status 401 and true challenge for /v1/ping
Debug: authenticated request for /v1/documents
Debug: digest authentication
Debug: writing 2 parts
Debug: starting part 0
Debug: finished part 0
Debug: starting part 1
Debug: finished part 1
Error: socket hang up
Debug: deferred promise rejecting with 1 error messages
node:_http_client:782
    emitErrorEvent(req, new ConnResetException('socket hang up'));
                        ^

Error: socket hang up
    at Socket.socketOnEnd (node:_http_client:782:25)
    at Socket.emit (node:events:526:24)
    at endReadableNT (node:internal/streams/readable:1772:12)
    at process.processTicksAndRejections (node:internal/process/task_queues:90:21) {
  code: 'ECONNRESET'
}

Node.js v26.6.0
node debug-write.mjs  0.18s user 0.10s system 0% cpu 32.055 total
➜ 

There is more than 15s between these two lines:

Debug: finished part 1
Error: socket hang up

In 8000_AccessLog.txt:

172.18.0.1 - - [06/Aug/2026:12:10:12 +0200] "HEAD /v1/ping HTTP/1.1" 401 0 - -
172.18.0.1 - admin [06/Aug/2026:12:10:44 +0200] "POST /v1/documents HTTP/1.1" 500 273 - -

In 8000_ErrorLog.txt:

2026-08-06 12:10:44.590 Info: Status 500: XDMP-MULTIPART-BOUNDARY: xdmp:get-request-part-body("json") -- Ending of the boundary is incorrect

Tested with 3.6.0 and 4.1.0. MarkLogic is 11.3.6.