v-link: handle null value (fix #181)

Author: yyx990803

src/directives/link.js

@@ -77,7 +77,7 @@ export default function (Vue) {
       this.updateClasses(this.vm.$route.path)
       let isAbsolute = path.charAt(0) === '/'
       // do not format non-hash relative paths
-      let href = router.mode === 'hash' || isAbsolute
+      let href = path && (router.mode === 'hash' || isAbsolute)
         ? router.history.formatPath(path, append)
         : path
       if (this.el.tagName === 'A') {

src/index.js

@@ -200,7 +200,9 @@ class Router {
       append = path.append
     }
     path = this._stringifyPath(path)
-    this.history.go(path, replace, append)
+    if (path) {
+      this.history.go(path, replace, append)
+    }
   }
 
   /**
@@ -505,7 +507,7 @@ class Router {
    */
 
   _stringifyPath (path) {
-    if (typeof path === 'object') {
+    if (path && typeof path === 'object') {
       if (path.name) {
         var params = path.params || {}
         if (path.query) {
@@ -518,7 +520,7 @@ class Router {
         return ''
       }
     } else {
-      return path + ''
+      return path ? path + '' : ''
     }
   }
 }