fix: enhance typings, update examples #32

[tzezar]

I updated the examples, they pass svelte-check now.

PS F:\GitHub\svelte-virtuallists> npm run check

> svelte-virtuallists@1.4.1 check
> svelte-kit sync && svelte-check --tsconfig ./tsconfig.json


====================================
Loading svelte-check in workspace: f:\GitHub\svelte-virtuallists
Getting Svelte diagnostics...

====================================
svelte-check found 0 errors and 0 warnings
PS F:\GitHub\svelte-virtuallists>

[orefalo]

thank you!