Can't delete text from Google Doc

I’m trying to amend cells in a Google doc using their api. But I can’t seem to delete text from the tableCell.

I always get the invalid deletion range error. There is this duplicate question.

But the solution is what I’m already doing:

let requests = [];
// I hold an instance of the table in the document.
// The getCellAt(…) is a function to return the tableCell object.
// It appears to work correctly: a breakpoint at this line and inspection
// of the cell variable confirms this.
let cell = this._tables[0].getCellAt(row, column);
cell.content.forEach((cntnt) => {
   cntnt.paragraph.elements.forEach((element) => {
       let deletion = getNewDeleteRequest();
       deletion.deleteContentRange.range.startIndex = element.startIndex;
       deletion.deleteContentRange.range.endIndex = element.endIndex - 1; //subtract 1 for the end newline
       deletion.deleteContentRange.range.tabId = this._documentTabID;
       // Ensure minimum of length 2
       let deletionRange = deletion.deleteContentRange.range.endIndex - deletion.deleteContentRange.range.startIndex;
       if (deletionRange > 1) { // avoids deleting paragraphs just with single new lines
            requests.push(deletion);
       }
    })
});


        
        return requests.reverse();

The helper function is:

/**
 * This is the structure for deleting text
 */
const deleteRequestTemplate = {
    deleteContentRange: {
        range: {
            startIndex: 10,
            endIndex: 50,
            tabId: "teb id"
        }
    }
}

// Return a perfect clone of the delete text template
function getNewDeleteRequest() {
    return structuredClone(deleteRequestTemplate);
}

Inserting text at the startIndex (using very similar helper function to the one above) works and subtracting 2 or 0 from the endIndex makes no difference.

As noted in one of the answers to the other SO question, there’s now only 5 of us using the api…..