yarn web: dragging and dropping vsix into extension explorer causes exception

[mjbvz]

Steps to Reproduce:

1. yarn web
2. Open in Chrome
3. Open extension view and drop a vsix onto it

Bug
Nothing happens.

In the dev tools, I see:

log.ts:301   ERR Cannot read property 'indexOf' of undefined: TypeError: Cannot read property 'indexOf' of undefined
    at Object.onDrop (http://localhost:8080/static/out/vs/workbench/contrib/extensions/browser/extensionsViewlet.js:458:42)
    at HTMLDivElement.<anonymous> (http://localhost:8080/static/out/vs/workbench/browser/dnd.js:398:32)

[mjbvz]

Seems like a duplicate of #106914 but @lszomoru can confirm if this isn't excepted to work

[lszomoru]

This is a feature request that is being tracked by #106914. Closing as duplicate.