Office Script to Check if Table Header Exists

I'm working on a macro in OfficeScript.
Among other things I need it to check if a column header exists in the given table and add a column if it doesn't exist. This part doesn't seem to work.

Here is the relevant snippet

function QAcolorTable(table: ExcelScript.Table){
  console.log("table: " + table.getName());
  
  //find or create column to for score formula
  let columnScore = table.getColumn("Score");
  console.log('null '+ (columnScore==null));
  console.log('type of ' + (typeof columnScore));
  console.log("undefined " + (columnScore==undefined));
  console.log("not " + !columnScore);
  console.log("void " + (columnScore == void 0));
  if (!columnScore) {
    console.log("adding 'Score'");
    table.addColumn(-1, null, "Score");
    columnScore = table.getColumn("Score");
  }
}

The office script documentation says that if getColumn should return 'undefined' if a column is not found, so I also tried number of tests for an undefined variable, but all return false.

https://learn.microsoft.com/en-us/ja...lumn-member(1)

So at this point I am thinking I may need to add a function to loop through all the headers, but that feels like overkill.
Any suggestions?

Here is my full code. I attached a sample workbook with appropriately named worksheet and table.

function main(workbook: ExcelScript.Workbook) {
  let sheets = workbook.getWorksheets();
  sheets.forEach(sheet => {
    let sheetName = sheet.getName();
    if(sheetName.search("QA Checklist") > -1){
      QA_color_Sheet(sheet);
    }
  });
}

function QA_color_Sheet(sheet : ExcelScript.Worksheet){
  console.log("sheet: " + sheet.getName() );
  let tables = sheet.getTables();
  tables.forEach(table => {
    let tableName = table.getName();
    if(tableName.search("QAChecklist") > -1) {
      QAcolorTable(table);
    }
  });
}

function QAcolorTable(table: ExcelScript.Table){
  console.log("table: " + table.getName());
  
  const scoreFormula = "=IF( [@[Consultant Checked]]=\"N/A\",NA(),SWITCH([@[Get Colour]],38, 1, 36, 0.5, 35, 0, \"#C6EFCE\", 0, \"#FFEB9C\", 0.5, \"#FFC7CE\", 1, 1))";
  let headers = table.getHeaderRowRange();

  //get the column object to read colours from Exit if not found.
  let columnRead = table.getColumn("Initial Reviewer Comments");
  if (!columnRead) { columnRead = table.getColumn("Reviewer Comments"); }
  if (!columnRead) {
    console.log("column [Initial Reviewer Comments]||[Initial Reviewer Comments] not found in " + table.getName());
    return;
  }
  let rngRead = columnRead.getRangeBetweenHeaderAndTotal();

  //find or create colum to write RGB color to. 
  let columnWrite = table.getColumn("Get Colour");
  if (!columnWrite){
    console.log("Adding 'Get Colour'");
    table.addColumn(-1, null, "Get Colour");
    columnWrite = table.getColumn("Get Colour");
  }
  let rngWrite = columnWrite.getRangeBetweenHeaderAndTotal();

  //find or create column to for score formula
  let columnScore = table.getColumn("Score");
  console.log('null '+ (columnScore==null));
  console.log('type of ' + (typeof columnScore));
  console.log("undefined " + (columnScore==undefined));
  console.log("not " + !columnScore);
  console.log("void " + (columnScore == void 0));
  if (!columnScore) {
    console.log("adding 'Score'");
    table.addColumn(-1, null, "Score");
    columnScore = table.getColumn("Score");
  }
  console.log(scoreFormula)
  columnScore.getRangeBetweenHeaderAndTotal().getCell(0,0).setFormula(scoreFormula);

  let rows = table.getRowCount();
  for (let rw = 0; rw < rows; rw++) {
    let cellColorRead = rngRead.getCell(rw, 0);
    let cellWrite = rngWrite.getCell(rw, 0);
    cellWrite.setValue(cellColorRead.getFormat().getFill().getColor());
  }
}