I dragged a document bookmark to a collection and one of the items in the collection vanished. The actual item represented in the collection is still to be found in the project.
Can I destroy documents doing this? Was I lucky? What happened?
There is absolutely no way by which you can destroy a document. (Of course, if you really put yourself into crashing the software then you might.)
The only possible “damaging” destination is otherwise the trash. And only you can empty it.
Was that document already in the collection ?
If you add to the collection a document that is already in it, it only moves it to the new emplacement. A document can’t be present twice.
You can trash items from a collection with the same shortcut you would use to trash them from the binder. Emphasis on “trash” though, not destroy. It is impossible to outright delete a binder item in one move.
But even trashing won’t happen by dragging a bookmark into the list. Worst case the collection list lost track of an item (some kind of bug), but it’s just a list of items, not the actual items themselves. We’d need some manner of reproduction checklist to verify the bug.
The item was already in the collection. I didn’t try to put it back. It was as if it was pushed out of the collection by the newly added item. They were different items.
No worries to have there.
Aside the inconvenience, nothing to fear.
As @AmberV said, these listed items (in a collection) are not even documents. They are only mirrored references to them.