fix: memory leak

[SpanManX]

In a low-code–like platform, elements from the left panel are dragged onto the canvas on the right to generate a component, and the dragged source element is removed. When the newly generated component is deleted, a memory leak occurs.

The multiDrag property is not properly checked, causing the following code to execute even when multiDrag is set to false:
delayStartGlobal({ dragEl: dragged }) { dragEl = dragged; }

When logging inside _onDrop, dragEl has already been removed from the DOM, but in MultiDrag.js, dragEl still retains a reference to the DOM node.

[SpanManX]

@owen-m1 Please review my code.

[owen-m1]

Thanks I've fixed it in a different way: 48b626b