Не отображаются колонки в диаграмме.
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.8.0/Chart.min.js"></script>
</head>
<body>
    <button>
        Запуск
    </button>
    <canvas id='chart'></canvas>
    <legend for="canvas"></legend>
    
    <script src="main.js"></script>
</body>
</html>
let button = document.querySelector('button');
button.onclick = function(){
    let wordsLength = [];
    let answer = prompt('Введи предложение');
    answer = answer.replace(/[^\w\s]/gi, "");
    let words = answer.split(' ');
    
    for (let i = 0; i < answer.length - 1; i++){
        let word = words[i];
        wordsLength.push(word.length);
    }
    var ctx = document.getElementById('chart');
    var myChart = new Chart(ctx, {
        type: 'bar',
        data: {
            labels: words,
            datasets: [{
                label: 'Количество букв',
                data: wordsLength,
                backgroundColor: [
                    'rgba(255, 99, 132, 0.2)'
                ],
                borderColor: [
                    'rgba(255, 99, 132, 1)'
                ],
                borderWidth: 1
            }]
        },
        options: {
            scales: {
                yAxes: [{
                    ticks: {
                        beginAtZero: true
                    }
                }]
            }
        }
    });
}