Allow null values as pipe parameters

src/array/merge.pipe.spec.ts

@@ -25,6 +25,21 @@ describe('MergePipe', () => {
     expect(result).toEqual([1, 2, 3, 4]);
   });
 
+  it('Should merge with null value', () => {
+    const result = pipe.transform([1, 2], null);
+    expect(result).toEqual([1, 2]);
+  });
+
+  it('Should merge on null value', () => {
+    const result = pipe.transform(null, [1, 2]);
+    expect(result).toEqual([1, 2]);
+  });
+
+  it('Should merge null values', () => {
+    const result = pipe.transform(null, null);
+    expect(result).toEqual([]);
+  })
+
   it('Should return an empty array', () => {
     expect(pipe.transform('a')).toEqual([]);
     expect(pipe.transform([], 'a')).toEqual([]);

src/array/merge.pipe.ts

@@ -1,11 +1,13 @@
 import { Pipe, PipeTransform, NgModule } from '@angular/core';
-import { isArray, isDeepObject, unwrapDeep, deepIndexOf } from '../utils/utils';
+import { isArray, isDeepObject, unwrapDeep } from '../utils/utils';
 
 @Pipe({
   name: 'merge',
 })
 export class MergePipe implements PipeTransform {
   transform(a?: any, b?: any): any {
+    a = a === null ? [] : a;
+    b = b === null ? [] : b;
     if ((!isArray(a) && !isDeepObject(a)) || !isArray(b)) {
       return [];
     }