fix dom is null

Author: jljsj33

package.json

@@ -1,6 +1,6 @@
 {
   "name": "rc-drawer-menu",
-  "version": "0.5.4",
+  "version": "0.5.5",
   "description": "drawer menu animation component for react",
   "keywords": [
     "react",

src/Drawer.jsx

@@ -154,6 +154,9 @@ class Drawer extends React.PureComponent {
   getScollDom = (dom) => {
     const doms = [];
     const setScrollDom = (d) => {
+      if (!d) {
+        return;
+      }
       if ((d.scrollHeight > d.clientHeight || d.scrollWidth > d.clientWidth)) {
         doms.push(d);
       }