title: Exceljs locking cell creates empty rows
body: <p>I need help in locking cells using excel js modules. I am using node js. I have created some dummy rows and added a formula. All I need is the user can only edit numerator and denominator columns. When I pass in getCell(<code>C1</code>).protection. All it does the header becomes editable. If I change it to C2. It inserts an empty row. Not sure what to do.
  I have looped over the rows array and tried locking cell + index + 1.
  Please guide me..</p>
  
  <p><a href="https://i.imgur.com/2f4Gis2.png" rel="nofollow noreferrer">ScreenShot</a></p>
  
  <p>Thanks
  Meet</p>
  
  <pre><code>const Excel = require('exceljs/modern.nodejs');
  const workbook = new Excel.Workbook();
  const worksheet = workbook.addWorksheet('ExampleSheet');
  
  worksheet.columns = [
    { header: 'Package', key: 'package_name' },
    { header: 'Author', key: 'author_name' },
    { header: 'N', key: 'num'},
    { header: 'D', key: 'dino'},
    { header: 'Computed', key: 'computed'}
  ];
  const rows = [
    { package_name: "FGH", author_name: "Author 4", num: 11, dino: 8, computed:{ formula: 'C2+D2' }},
    { package_name: "PQR", author_name: "Author 5", num: 10, dino: 4, computed:{ formula: 'C3+D3' }}
  ];
  
  rows.forEach((el, i) =&gt; {
    console.log(`C${i+1}`)
    worksheet.getCell(`C${i+1}`).protection = {
      locked: false
    };
    worksheet.getCell(`D${i+1}`).protection = {
      locked: false
    }
  });
  
  const func = async() =&gt; {
    const res = await worksheet.protect('password', {selectUnlockedCells: true});
    console.log(res);
  }
  func();
  
  worksheet
    .addRows(rows);
  
  workbook
    .xlsx
    .writeFile('sample.xlsx')
    .then(() =&gt; {
      console.log("saved");
    })
    .catch((err) =&gt; {
      console.log("err", err);
    });
  </code></pre>