Task: Save email attachments to Nextcloud

n8n workflow:
{"nodes":[{"name":"IMAP Email","type":"n8n-nodes-base.emailReadImap","position":[240,420],"parameters":{"format":"resolved","mailbox":"Invoices","options":{"customEmailConfig":"[\"ALL\"]"}},"typeVersion":1},{"name":"Nextcloud","type":"n8n-nodes-base.nextCloud","position":[940,420],"parameters":{"path":"=Documents/Invoices/{{$json[\"date\"]}}_{{$json[\"from\"]}}_{{$binary.file.fileName}}","binaryDataUpload":true,"binaryPropertyName":"file"},"typeVersion":1},{"name":"Map each attachment","type":"n8n-nodes-base.function","position":[620,420],"parameters":{"functionCode":"const _ = require('lodash')\n\nconst sanitize = str => _.chain(str)\n  .replace(/[^A-Za-z0-9&.-]/g, '-') // sanitise via whitelist of characters\n  .replace(/-(?=-)/g, '') // remove repeated dashes - https://regexr.com/6ag8h\n  .trim('-') // trim any leading/trailing dashes\n  .truncate({\n    length: 60,\n    omission: '-' // when the string ends with '-', you'll know it was truncated\n  })\n  .value()\n\nconst result = _.flatMap(items.map(item => {\n  //console.log({item})\n\n  // Maps each attachment to a separate item\n  return _.values(item.binary).map(file => {\n    console.log(\"Saving attachement:\", file.fileName, 'from:', ...item.json.from.value)\n    \n    // sanitize filename but exclude extension\n    const filename_parts = file.fileName.split('.')\n    const ext = _.slice(filename_parts, filename_parts.length-1)\n    const filename_main = _.join(_.dropRight(filename_parts), '.')\n    file.fileName = sanitize(filename_main) + '.' + ext\n    \n    return {\n      json: {\n        from: sanitize(item.json.from.value[0].name),\n        date: sanitize(new Date(item.json.date).toISOString().split(\"T\")[0]) // get date part \"2020-01-01\"\n      }, \n      binary: { file }\n    }\n  })\n}))\n\n//console.log(result)\nreturn result"},"typeVersion":1}],"connections":{"IMAP Email":{"main":[[{"node":"Map each attachment","type":"main","index":0}]]},"Map each attachment":{"main":[[{"node":"Nextcloud","type":"main","index":0}]]}}}