6b724616c0
This change disallows calling `mjs_delete` on an mjSpec that has been attached to another mjSpec via `mjs_attach`. Attempting to delete an element from an attached spec will now result in an error. The Python bindings for `mjSpec.delete` have been updated to raise a ValueError when this occurs. PiperOrigin-RevId: 897266695 Change-Id: Ic0670125a3028191ec50eca890f02b5910ec8b03