Generic distribution problem in TypeScript

README.md

I don't know why distribution affect to problems.

generic-distribution.ts

type Test1<T> = {
    [K in keyof T]:
        T[K] extends string ? { string: true } :
        T[K] extends number ? { number: true } :
        T[K] extends object ? Test1<T[K]> :
        never;
};

type Test3<T> = T extends T ? {
    [K in keyof T]:
        T[K] extends string ? { string: true } :
        T[K] extends number ? { number: true } :
        T[K] extends object ? Test3<T[K]> :
        never;
} : never;

function A<T extends { a: string }>() {
    let a: Test1<T> = null as any;
    let b: Test1<{a:string}> = null as any;
    a.a.string; // ERROR: any, Property 'string' does not exist on type 'T["a"] extends string ? { string: true; } : T["a"] extends number ? { number: true; } : T["a"] extends object ? Test1<T["a"]> : never'.(2339)
    b.a.string;

    let e: Test3<T> = null as any;
    let f: Test3<{a:string}> = null as any;
    e.a.string;
    f.a.string;
}