From b096ba36397c261143a17165c40fc3dc90cf825e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C4=B0smail=20Ar=C4=B1l=C4=B1k?= <arilik.ismail@gmail.com>
Date: Thu, 8 Mar 2018 18:31:40 +0300
Subject: [PATCH] polish: raise warning when Vue.set/delete is called on
 invalid values  (#7452)

close #7381
---
 src/core/observer/index.js                  | 12 ++++++++++++
 test/unit/modules/observer/observer.spec.js | 12 ++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/src/core/observer/index.js b/src/core/observer/index.js
index 244876b2172..2ce0aabd2c9 100644
--- a/src/core/observer/index.js
+++ b/src/core/observer/index.js
@@ -194,6 +194,12 @@ export function defineReactive (
  * already exist.
  */
 export function set (target: Array<any> | Object, key: any, val: any): any {
+  if (process.env.NODE_ENV !== 'production' &&
+    !Array.isArray(target) &&
+    !isObject(target)
+  ) {
+    warn(`Cannot set reactive property on non-object/array value: ${target}`)
+  }
   if (Array.isArray(target) && isValidArrayIndex(key)) {
     target.length = Math.max(target.length, key)
     target.splice(key, 1, val)
@@ -224,6 +230,12 @@ export function set (target: Array<any> | Object, key: any, val: any): any {
  * Delete a property and trigger change if necessary.
  */
 export function del (target: Array<any> | Object, key: any) {
+  if (process.env.NODE_ENV !== 'production' &&
+    !Array.isArray(target) &&
+    !isObject(target)
+  ) {
+    warn(`Cannot delete reactive property on non-object/array value: ${target}`)
+  }
   if (Array.isArray(target) && isValidArrayIndex(key)) {
     target.splice(key, 1)
     return
diff --git a/test/unit/modules/observer/observer.spec.js b/test/unit/modules/observer/observer.spec.js
index 3ed7a3a48c3..2002682328c 100644
--- a/test/unit/modules/observer/observer.spec.js
+++ b/test/unit/modules/observer/observer.spec.js
@@ -356,6 +356,18 @@ describe('Observer', () => {
     })
   })
 
+  it('warn set/delete on non valid values', () => {
+    try {
+      setProp(null, 'foo', 1)
+    } catch (e) {}
+    expect(`Cannot set reactive property on non-object/array value`).toHaveBeenWarned()
+
+    try {
+      delProp(null, 'foo')
+    } catch (e) {}
+    expect(`Cannot delete reactive property on non-object/array value`).toHaveBeenWarned()
+  })
+
   it('should lazy invoke existing getters', () => {
     const obj = {}
     let called = false