fix vuejs#716 unwatch causing error during destroy

yyx990803 · yyx990803 · commit 515195ad76cd · 2015-02-19T12:15:45.000-08:00
diff --git a/src/instance/compile.js b/src/instance/compile.js
@@ -143,8 +143,12 @@ exports._destroy = function (remove, deferCleanup) {
     this._directives[i]._teardown()
   }
   // teardown all user watchers.
+  var watcher
   for (i in this._userWatchers) {
-    this._userWatchers[i].teardown()
+    watcher = this._userWatchers[i]
+    if (watcher) {
+      watcher.teardown()
+    }
   }
   // remove reference to self on $el
   if (this.$el) {

Original file line number	Diff line number	Diff line change
`@@ -143,8 +143,12 @@ exports._destroy = function (remove, deferCleanup) {`
`143`	`143`	`this._directives[i]._teardown()`
`144`	`144`	`}`
`145`	`145`	`// teardown all user watchers.`
	`146`	`+ var watcher`
`146`	`147`	`for (i in this._userWatchers) {`
`147`		`- this._userWatchers[i].teardown()`
	`148`	`+ watcher = this._userWatchers[i]`
	`149`	`+ if (watcher) {`
	`150`	`+ watcher.teardown()`
	`151`	`+ }`
`148`	`152`	`}`
`149`	`153`	`// remove reference to self on $el`
`150`	`154`	`if (this.$el) {`