fix .getAttribute on an object without this method (#967)

Author: AnthonySendra

src/components/link.js

@@ -94,8 +94,10 @@ function guardEvent (e) {
   if (e.button !== 0) return
   // don't redirect if `target="_blank"`
   /* istanbul ignore if */
-  const target = e.target.getAttribute('target')
-  if (/\b_blank\b/i.test(target)) return
+  if (e.target && e.target.getAttribute) {
+    const target = e.target.getAttribute('target')
+    if (/\b_blank\b/i.test(target)) return
+  }
 
   e.preventDefault()
   return true