I’m working on a Chrome extension side panel. Part of it inserts text into a Google Doc open in Doc Picker as a paragraph style heading, like heading 2 for example.

I’ve been following the Google Docs API documentation and have tried using other example like the one here “/questions/70721569/how-add-styled-paragraphs-in-google-document-by-api”, “How add styled paragraphs in Google Document by API”, but without any luck. The only error I get is error status 15, and that is only sometimes.

The tags are either inserted as plain text or not inserted at all.

Here’s a simplified version of the code I’m using to insert the tags:

function insertIntoDoc(url, text, tags, insertionPosition, sendResponse) {
  // ...

  if (tags && tags.length > 0) {
    tags.forEach(tag => {
      requests.push({
        insertText: {
          text: `${tag}n`,
          endOfSegmentLocation: {},
        },
      });
      requests.push({
        updateParagraphStyle: {
          range: {
            startIndex: -tag.length - 1,
            endIndex: -1,
          },
          paragraphStyle: {
            namedStyleType: 'HEADING_2',
          },
          fields: 'namedStyleType',
        },
      });
    });
  }

  // ...
}

I’ve double-checked that I have the necessary permissions in the manifest.json file and that the OAuth2 setup is correct for accessing the Google Docs API. I know because it does insert the text, just not as a heading. Any help would be greatly appreciated. Thanks in advance any help or guidance you can give me!