fix subscribe

src/register.ts

@@ -14,7 +14,7 @@ import {
 } from './utility';
 import { DoRegister } from './registry';
 import _ from 'lodash';
-import { isObservable, Observable } from 'rxjs';
+import { isObservable, Observable, of } from 'rxjs';
 
 export interface DoRegisterResult<T> extends DoRegister.Config {
   key: keyof T & string;
@@ -82,11 +82,15 @@ export class Registrar<T = any> {
     ctx: Context,
     cb: ContextFunction<R>,
     layers: ContextCallbackLayer[],
-  ) {
+  ): Observable<R extends Observable<infer U> ? U : Awaited<R>> {
     const rest = [...layers];
     const layer = rest.pop();
-    return new Observable<R extends Observable<infer U> ? U : Awaited<R>>(
-      (subscriber) => {
+    if (!layer) {
+      // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+      // @ts-ignore
+      return of(cb(ctx));
+    }
+    return new Observable((subscriber) => {
       layer(ctx, async (nextCtx) => {
         if (!rest.length) {
           const result = cb(nextCtx);
@@ -108,8 +112,7 @@ export class Registrar<T = any> {
           this.runLayersWith(nextCtx, cb, rest).subscribe(subscriber);
         }
       });
-      },
-    );
+    });
   }
 
   runLayers<R>(ctx: Context, cb: ContextFunction<R>, key?: keyof T) {

tests/register.spec.ts

@@ -149,11 +149,13 @@ describe('Register', () => {
   });
 
   it('should work with layers', () => {
-    registrar.runLayers(
+    registrar
+      .runLayers(
         app,
         (ctx) => registrar.register(app, 'unUnderwear'),
         'unUnderwear',
-    );
+      )
+      .subscribe();
     expect(app['foo']).toBe(1);
     expect(app['bar']).toBe(2);
   });