I’m trying to re run a formula that sums all of the cells with a certain color. When I call the function, it runs correctly. After I add a another cell with the same colour it should re run and increase the number by 1. If I delete the cell and then type in the function again it works. Here is the code for the function

function countColoredCells(countRange, colorRef) {
  const ss = SpreadsheetApp.getActive();
  const formula = ss.getActiveRange().getFormula();
  let searchColor, countRangeA1;
  try {
    const colorRefA1 = formula.match(/,(.+))/).pop().trim();
    searchColor = ss.getActiveSheet().getRange(colorRefA1).getBackground();
    countRangeA1 = formula.match(/((.+),/).pop().trim();
  } catch (error) {
    throw new Error('Bad arguments.');
  }
  let count = 0;
  ss.getSheets().forEach(sheet => {
    count += sheet.getRange(countRangeA1).getBackgrounds()
      .flat()
      .filter(c => c === searchColor)
      .length
  });
  return count;
}

Here is the line calling the function:
=countColoredCells(A:A,’Practice Sheet’!A6)

When I manually run the function again I get an error on line 10. I want the cell to update atomatically on spreadsheet changes.

I tried to add a trigger on spreadsheet changes but it gives me the same error as mentioned above and the code fails.