Tree: set isCurrent prop to False (#15870)

packages/tree/src/model/tree-store.js

@@ -327,8 +327,8 @@ export default class TreeStore {
   }
 
   setCurrentNodeKey(key) {
-    if (key === null) {
-      this.currentNode.isCurrent = false;
+    if (key === null || key === undefined) {
+      this.currentNode && (this.currentNode.isCurrent = false);
       this.currentNode = null;
       return;
     }