Error message "Header not defined" in Apps Script - google-apps-script

Question

I am trying to pull data from google sheet into google form to create a dropdown list in the google form. the Script that I copied from the internet is throwing an error with the message "Header is not defined". Can someone please tell me what changes to make in the script to make this script work? the debugger says error is in line 6.
function getDataFromGoogleSheets() {
const ss = SpreadsheetApp.getActiveSpreadsheet();
const sheet = ss.getSheetByName("CompanyName");
const data = sheet.getDataRange().getDisplayValue();
const choices = {}
header.forEach(function(title,index){
choices[title] = data.map(row=>row [index]).filter(e=>e!=="");
});
return choices;
}
function populateGoogleForms(){
const GOOGLE_FORM_ID = "1H80nNJXb3hekZp7CZOZ0FGNpEwCiQnpHL17y3w8WSNk";
const googleForm = FormApp.openById(GOOGLE_FORM_ID);
const items = googleForm.getItems();
const choices = getDataFromGoogleSheets();
items.forEach(function(item){
const itemTitle = item.getTitle();
if(itemTitle in choices) {
const itemType = item.getType();
switch (itemType){
case FormApp.ItemType.LIST:
item.asListItem().setChoiceValues(choices[itemTitle]);
break;
default:
Logger.log("ignore question", itemTitle)
}
}
});
}

Answer 1

function getDataFromGoogleSheets() {
const ss = SpreadsheetApp.getActiveSpreadsheet();
const sheet = ss.getSheetByName("CompanyName");
const data = sheet.getDataRange().getDisplayValue();//this should be getDisplayValues();
const choices = {}
header.forEach(function(title,index){//you have not defined header
choices[title] = data.map(row=>row [index]).filter(e=>e!=="");
});
return choices;
}
I might guess that it could be as simple as this
const [header, ... data] = sheet.getDataRange().getDisplayValues();
But I'd have to know more about your spreadsheet to be sure.