From 7cec79d339b874ec41f35891c891dfd27460c1d3 Mon Sep 17 00:00:00 2001
From: Kia King Ishii <kia.king.08@gmail.com>
Date: Mon, 29 Jun 2020 23:53:53 +0900
Subject: [PATCH] fix: warn when unregistering non existing module (#1786)

* fix: warn when unregistering non existing module

* refactor: store child as a variable and reuse it
---
 src/module/module-collection.js            | 16 +++++++++++++++-
 test/unit/module/module-collection.spec.js |  8 ++++++++
 2 files changed, 23 insertions(+), 1 deletion(-)

diff --git a/src/module/module-collection.js b/src/module/module-collection.js
index ee1a887ba..095872882 100644
--- a/src/module/module-collection.js
+++ b/src/module/module-collection.js
@@ -49,7 +49,21 @@ export default class ModuleCollection {
   unregister (path) {
     const parent = this.get(path.slice(0, -1))
     const key = path[path.length - 1]
-    if (!parent.getChild(key).runtime) return
+    const child = parent.getChild(key)
+
+    if (!child) {
+      if (__DEV__) {
+        console.warn(
+          `[vuex] trying to unregister module '${key}', which is ` +
+          `not registered`
+        )
+      }
+      return
+    }
+
+    if (!child.runtime) {
+      return
+    }
 
     parent.removeChild(key)
   }
diff --git a/test/unit/module/module-collection.spec.js b/test/unit/module/module-collection.spec.js
index 007989af2..3e8081ce3 100644
--- a/test/unit/module/module-collection.spec.js
+++ b/test/unit/module/module-collection.spec.js
@@ -92,4 +92,12 @@ describe('ModuleCollection', () => {
     collection.unregister(['a'])
     expect(collection.get(['a']).state.value).toBe(true)
   })
+
+  it('warns when unregistering non existing module', () => {
+    const spy = jest.spyOn(console, 'warn').mockImplementation()
+
+    const collection = new ModuleCollection({})
+    collection.unregister(['a'])
+    expect(spy).toHaveBeenCalled()
+  })
 })