Не выводится сообщение после анимации

  function go() {
    showCircle(150, 150, 100).then(div =>{
       div.classList.add('message-ball');
       div.append("Hello, world!");
    });
  }

  function showCircle(cx, cy, radius) {
    let div = document.createElement('div');
    div.style.width = 0;
    div.style.height = 0;
    div.style.left = cx + 'px';
    div.style.top = cy + 'px';
    div.className = 'circle';
    document.body.append(div);

    setTimeout(() => {
      div.style.width = radius * 2 + 'px';
      div.style.height = radius * 2 + 'px';

      div.addEventListener('transitionend', function handler() {
        div.removeEventListener('transitionend', handler);
        return new Promise((resolve, reject) =>{
        resolve(div);
      })
      });
    });
  }

 .message-ball {
      font-size: 20px;
      line-height: 200px;
      text-align: center;
    }
    .circle {
      transition-property: width, height, margin-left, margin-top;
      transition-duration: 2s;
      position: fixed;
      transform: translateX(-50%) translateY(-50%);
      background-color: red;
      border-radius: 50%;
    }

  <button onclick="go()">Click me</button>