type T = any extends number ? 1 : 0;
let x: T;
x = 1;
x = 0;

type DeepMapAsObject<T> = T extends object | undefined
? {
    [K in keyof T]: T[K] extends Map<infer KM, infer KV> | undefined
    // if it's a map, transform it into Map | Record
    // only string keys allowed
    ? KM extends string ? Map<KM, DeepMapAsObject<KV>> | Record<KM, DeepMapAsObject<KV>> | [KM, DeepMapAsObject<KV>][] : never
    // otherwise if it's an object or undefined (for optional props), recursively go again
    : T[K] extends object | undefined
      ? DeepMapAsObject<T[K]>
      : T[K]
    }
: T;

type DeepMapAsObject<any[]> = { /* since any[] extends object */
    // keyof any[] is number, any[number] is any
    [number]: any extends Map<unknown, unknown> | undefined // these get inferred as unknown
    // if it's a map, transform it into Map | Record
    // only string keys allowed
    ? never // KM is unknown which does not extend string, result is never
    // otherwise if it's an object or undefined (for optional props), recursively go again
    : any extends object | undefined
      ? DeepMapAsObject<any> // not too clear what happens here... I think this becomes { [K in string]: never | any } in previous versions of typescript, and { [K in string]: never } in the current version 
      : any
    };