fix: return type of merge result

src/type.ts

@@ -5,7 +5,13 @@
  * view the LICENSE file that was distributed with this source code.
  */
 
-export type MergerResult<A, B> = A extends B ? B extends A ? A : (A & B) : (A & B);
+export type MergerResult<A, B> = A extends B ?
+    B extends A ?
+        // eslint-disable-next-line @typescript-eslint/ban-types
+        (A extends {} ? B : A) :
+        (A & B) :
+    (A & B);
+
 export type Merger = <A extends Record<string, any>, B extends Record<string, any>>(target: A, ...sources: B[]) => MergerResult<A, B>;
 
 export type Options = {

test/unit/module.spec.ts

@@ -146,5 +146,16 @@ describe('src/module/*.ts', () => {
         let merger = createMerger({priority: 'right'});
         const merged = merger( {prototype: null}, {prototype: 1});
         expect(merged).toEqual({prototype: null})
+    });
+
+    it('should return optimized return type', () => {
+        let item : Record<string, any> = {
+            id: 1,
+            name: 'admin'
+        }
+
+        let data = merge({}, item);
+        expect(data.id).toEqual(1);
+        expect(data.name).toEqual('admin');
     })
 })