This cleans up a couple of assumptions about the state of the world that
break down in multiplayer contexts:
1. updated shapes still exist while redoing
2. redoing the delete of a page that I am on will also redo switching
away from that page
### Change Type
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- [x] `patch` — Bug Fix
- [ ] `minor` — New Feature
- [ ] `major` — Breaking Change
- [ ] `dependencies` — Dependency Update (publishes a `patch` release,
for devDependencies use `internal`)
- [ ] `documentation` — Changes to the documentation only (will not
publish a new version)
- [ ] `tests` — Changes to any testing-related code only (will not
publish a new version)
- [ ] `internal` — Any other changes that don't affect the published
package (will not publish a new version)
### Release Notes
- Fixes a couple of minor consistency bugs affecting shape updating and
page deletion in multiplayer contexts.
16b7b07e1a