Revert "refactor: export internal types"

This reverts commit 4227f9d.

src/index.ts

@@ -9,4 +9,4 @@ export type {Registration, RegistrationMap, RegistrationOptions, Registry} from
 export {Build, Value} from "./registry";
 export {Scope} from "./scope";
 export type {Constructor, Token, TokenList} from "./token";
-export {Type, TypeNull, TypeUndefined} from "./token";
+export {Type} from "./token";

src/token.ts

@@ -26,15 +26,12 @@ export function Type<T>(typeName: string): Type<T> {
 }
 
 export declare namespace Type {
-  export var Null: typeof TypeNull;
-  export var Undefined: typeof TypeUndefined;
+  export var Null: Type<null>;
+  export var Undefined: Type<undefined>;
 }
 
-export const TypeNull: Type<null> = Type("null");
-export const TypeUndefined: Type<undefined> = Type("undefined");
-
-Type.Null = TypeNull;
-Type.Undefined = TypeUndefined;
+Type.Null = Type("null");
+Type.Undefined = Type("undefined");
 
 export interface Constructor<Instance extends object> {
   new (...args: []): Instance;