Issue with using the sanity client to patch plain text into a portable text field causing errors in the studio.

export function buildPortableTextField(plainText) {
  if (!plainText || plainText.length === 0) {
    return undefined;
  }

  return plainText.split('\n').map(text => ({
    style: 'normal',
    _type: 'block',
    children: [
      {
        _type: 'span',
        marks: [],
        text,
      },
    ],
    markDefs: [],
  }));
}

  "venueNotes": [
    {
      "_key": "BRtXrh1tOMb9vrrsTlm25B",
      "_type": "block",
      "children": [
        {
          "_key": "BRtXrh1tOMb9vrrsTlm2Ap",
          "_type": "span",
          "marks": [],
          "text": "Note line 1"
        }
      ],
      "markDefs": [],
      "style": "normal"
    },
    {
      "_key": "BRtXrh1tOMb9vrrsTlm2GT",
      "_type": "block",
      "children": [
        {
          "_key": "BRtXrh1tOMb9vrrsTlm2M7",
          "_type": "span",
          "marks": [],
          "text": "Note line 2"
        }
      ],
      "markDefs": [],
      "style": "normal"
    }
  ],