add null check in map._ignoreEvent

Author: fuzhenn

src/map/Map.DomEvents.js

@@ -245,7 +245,7 @@ Map.include(/** @lends Map.prototype */ {
         if (target) {
             while (target && target !== this._containerDOM) {
                 if (target.className && target.className.indexOf &&
-                    (target.className.indexOf('maptalks-control') >= 0  || (target.className.indexOf('maptalks-ui') >= 0 && !preTarget['eventsPropagation']))) {
+                    (target.className.indexOf('maptalks-control') >= 0  || (target.className.indexOf('maptalks-ui') >= 0 && preTarget && !preTarget['eventsPropagation']))) {
                     return true;
                 }
                 preTarget = target;

src/map/Map.Topo.js

@@ -1,5 +1,5 @@
 import { INTERNAL_LAYER_PREFIX } from '../core/Constants';
-import { extend, isString, isArrayHasData, pushIn } from '../core/util';
+import { isString, isArrayHasData, pushIn } from '../core/util';
 import Coordinate from '../geo/Coordinate';
 import Point from '../geo/Point';
 import Map from './Map';