Fix error from adding blank target to external links

[draganescu]

Motivation for the change, related issues

We use playground as a preview tool inside an app that generates WordPress blocks via AI assistant. We encounter JavaScript Error: TypeError: e.target.closest is not a function coming from Playground and it encumbers our assisted error recovery because it comes from outside of the generated code.

Implementation details

We don't attempt to update the link if the element surprisingly doesn't have a closest method (which is why we also log the element to see why this happens)

Testing Instructions (or ideally a Blueprint)

Hard to figure out, sometimes it occurs.

[adamziel]

Turns out e.target is of type EventTarget that also covers Document, Window, and other data types without the .closest() method – see MDN. I've removed the console log and documented the guard.