Cannot read properties of undefined (reading 'assignedSlot')

控制台报错：

Uncaught TypeError: Cannot read properties of undefined (reading 'assignedSlot')
    at yn (mdui.global.js:12:27064)
    at wn (mdui.global.js:12:27268)
    at kn (mdui.global.js:12:27545)
    at e.Tooltip.connectedCallback (mdui.global.js:22:76501)

代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Test</title>
    <link rel="stylesheet" href="https://unpkg.com/mdui@2/mdui.css">
    <script src="https://unpkg.com/mdui@2/mdui.global.js"></script>
</head>
<body>
<mdui-tooltip content="Plain tooltip">
  <mdui-button>button</mdui-button>
</mdui-tooltip>
</body>
</html>

zdhxiong / mdui

Cannot read properties of undefined (reading 'assignedSlot') #357