Types aren't properly loaded into environment until watcher runs

[danielroe]

When starting vue-tsc or Volar, types are not fully resolved and errors can't be checked until the first watch event occurs.

Reproduction: https://stackblitz.com/edit/github-dhpjw5?file=app.vue,package.json

To reproduce, open app.vue (while vue-tsc --watch is running) and edit the file, even just adding a comment would do. (This also works if you edit or create another file in the project.)

Possibly linked? #1274