fix: force emit types even when there're errors

[hyrious]

The dts plugin runs TypeScript to generate .d.ts files for .ts inputs. This often just works. However in some cases it still fails to fetch types from deep dependencies. I used to turn off all strict type-checking options to get rid of these errors, but today I found a special case which doesn't work in any option settings:

// @ts-expect-error
expectString(null)

function expectString(a: string) {}

1. If strictNullChecks: false, the code above raises Unused '@ts-expect-error' directive.
2. If I remove the directive, the code above cannot pass my projects type checking.

I only want to generate and bundle types and don't want to handle any type errors. So today I found that the TypeScript Playground actually can emit types even when there're errors in the code. After digging a while I found the hidden option to force emitting types.