Selecting multipe Node Elements

I have a problem when:

```
const taskItems = document.querySelectorAll('.task-item');
Array.from(taskItems).forEach(item => {
pan = new Pan(item);
}
```

...i get:
Uncaught TypeError: Cannot read properties of undefined (reading 'update') at HTMLBodyElement.dragMove (pan.js:143:38)

Reproduce the error by creating a Pan instance for each element returned by document.querySelectorAll('.task-item'). Start in pan.js at dragMove, line 143, and trace why update is read from undefined during the shared body drag handler. Done means dragging any of the selected elements no longer throws this error.

Written by the indexing model from the issue text.