i am not sure why it is saying unexpected end of input when i try to run the program.

//print function
function print(message) {
  document.write(message);
}
function printlist(arr){
// prints the questions you got right
  var listHTML = '<ul>';
  for(i = 0; i < arr.length; i += 1) {
    // creates a list
    listHTML += '<li>' + arr[i] + '</li>';
    listHTML += '</ul>';
    return(listHTML);
  }
}


// 2 demensional array with question, answer combo arrays inside
var questions = [
  ["What programming language is named after an animal?", "python"],
  ["What programming language is named after a stone?", "ruby"],
  ["What programming language is being used to run this program?", "javascript"],
  ["what is another programming language also named after coffee?", "java"]
];
var html;
var answer;
var numberCorrect = 0;
var numberIncorrect = 0;
var questionsCorrect = [];
var questionsIncorrect = [];
// rotates through the questions array and askes them in a pop up box
for (var i = 0; i < questions.length; i += 1) {
  answer = prompt(questions[i][0] + '\n correct answers ' + numberCorrect + '\n incorrect answers ' + numberIncorrect);
  // adds the questions values to a new set of arrays for questions you answered
  // correctley and incorrectly
  if(answer.toLowerCase() === questions[i][1]) {
    numberCorrect += 1;
    questionsCorrect.push(questions[i][0]);
    console.log(questionsCorrect);
  }else{
    numberIncorrect += 1;
    questionsIncorrect.push(questions[i][0]);
    console.log(questionsIncorrect);
  }
  console.log(numberCorrect);
}
html += '<p>total correctly answered: ' + numberCorrect + '<br> total incorrect answers: ' + numberIncorrect + '</p> <br>';
html += '<h2> these are the questions you answered correctly </h2>';
html += printlist(questionsCorrect);
print(html);