fix(compiler): Align return types of ErrImp<E> and OkImpl<T> with Result<T, E> for TS 5.5

[nikeee]

Summary

Result<T, E> defines isOk and isErr as type predicates:

  // Returns `true` if the result is `Ok`.
  isOk(): this is OkImpl<T>;
  // Returns `true` if the result is `Err`.
  isErr(): this is ErrImpl<E>;

The implementations just return boolean, which seems to break in TS 5.5:

Running tsc in current main:

tsc
src/Utils/Result.ts:202:3 - error TS2416: Property 'isOk' in type 'ErrImpl<E>' is not assignable to the same property in base type 'Result<never, E>'.
  Type '() => boolean' is not assignable to type '() => this is OkImpl<never>'.
    Signature '(): boolean' must be a type predicate.

202   isOk(): boolean {
      ~~~~

src/Utils/Result.ts:206:3 - error TS2416: Property 'isErr' in type 'ErrImpl<E>' is not assignable to the same property in base type 'Result<never, E>'.
  Type '() => boolean' is not assignable to type '() => this is ErrImpl<E>'.
    Signature '(): boolean' must be a type predicate.

206   isErr(): boolean {


Found 38 errors in 7 files.

Errors  Files
     2  src/HIR/BuildHIR.ts:196
     2  src/HIR/Environment.ts:745
     2  src/ReactiveScopes/CodegenReactiveFunction.ts:290
    14  src/Utils/Result.ts:96
     2  src/Validation/ValidateNoRefAccesInRender.ts:201
     2  src/Validation/ValidateNoSetStateInRender.ts:115
    14  src/__tests__/Result-test.ts:13

How did you test this change?

tsc
# no errors
tsc --version
Version 5.5.3

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Name	Status	Preview	Comments	Updated (UTC)
react-compiler-playground	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Jul 16, 2024 11:02am

[poteto]

Thanks!