Popover: fix reference error in the loop (#11503)

* Popover: fix reference error in the loop

* Update directive.js

packages/popover/src/directive.js

@@ -2,7 +2,11 @@ const getReference = (el, binding, vnode) => {
   const _ref = binding.expression ? binding.value : binding.arg;
   const popper = vnode.context.$refs[_ref];
   if (popper) {
-    popper.$refs.reference = el;
+    if (Array.isArray(popper)) {
+      popper[0].$refs.reference = el;
+    } else {
+      popper.$refs.reference = el;
+    }
   }
 };