fix(isPlainObject): support check Object.create(null) (#4633)

Co-authored-by: Tim Dorr <[email protected]>

Author: zhe-he

src/utils/isPlainObject.ts

@@ -10,5 +10,5 @@ export default function isPlainObject(obj: any): obj is object {
     proto = Object.getPrototypeOf(proto)
   }
 
-  return Object.getPrototypeOf(obj) === proto
+  return Object.getPrototypeOf(obj) === proto || Object.getPrototypeOf(obj) === null
 }

test/utils/isPlainObject.spec.ts

@@ -12,5 +12,6 @@ describe('isPlainObject', () => {
     expect(isPlainObject(null)).toBe(false)
     expect(isPlainObject(undefined)).toBe(false)
     expect(isPlainObject({ x: 1, y: 2 })).toBe(true)
+    expect(isPlainObject(Object.create(null))).toBe(true)
   })
 })