## Bug
- [x] Related issues linked using `fixes #number` fixes https://github.com/vercel/next.js/issues/27290
- [ ] Integration tests added
- [ ] Errors have helpful link attached, see `contributing.md`
## Feature
- [ ] Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
- [ ] Related issues linked using `fixes #number`
- [ ] Integration tests added
- [ ] Documentation added
- [ ] Telemetry added. In case of a feature if it's used or not.
- [ ] Errors have helpful link attached, see `contributing.md`
## Documentation / Examples
- [x] Make sure the linting passes
The mobx-state-tree examples (with and without typescript) pre-dated the next _app class and needed to be updated to use _app for persisting state across client-side navigation transitions. Also removed unneeded custom server class to better keep with the "show one feature per example" style of the next examples folder
I think I accidentally deleted the branch my prior PR was based on before you had a chance to merge or decide whether to merge. In case I borked things with that delete, I'm resubmitting the PR and figuring you can close one or the other or both as desired.
Original notes:
Based on with-mobx-state-tree, but typescript instead of javascript
Aside from a few bits of typing and renaming .js files to .ts and .tsx, most of the the edits are to avoid warnings and errors when running the code through tslint (which can be done via the `npm run tslint` command in the example if desired).
To keep this example simple, the `<styled>` component (which is used by the javascript-based with-redux and with-mobx-state-tree examples for the clock component) is not used in this example. The `<styled>` library can of course be used with typescript but (I think) it requires a more complicated set of typescript and babel .configs than is needed for most other components and libraries, so I'm just directly styling the one formerly `<styled>` div to keep things simple and broadly applicable.
