If you typo'd an `expect` property, you got a cryptic error message:
```
Uncaught TypeError: Cannot create proxy with a non-object as target or handler
```
Now we get this nice friendly message:
```
1) a.spec.ts:6:9 › explodes ======================================================================
Error: expect: Property 'toBeLessThen' not found.
Did you mean 'toBeLessThan'?
See https://playwright.dev/docs/test-assertions for available options and documentation.
5 | const { test } = pwt;
6 | test('explodes', () => {
> 7 | expect.soft(1).toBeLessThen();
| ^
8 | });
9 |
```
Fixes#13218
- Source now lives at `src/test`.
- Former folio tests live at `tests/playwright-test`.
- We use `src/test/internal.ts` that exposes base test without
Playwright fixtures for most tests (to avoid modifications for now).
- Test types live in `types/testFoo.d.ts`.
- Stable test runner is installed to `tests/config/test-runner` during `npm install`.
- All deps including test-only are now listed in `package.json`.
Non-test deps must also be listed in `build_package.js` to get included.
