productList判空 --review by 王海元

@@ -73,9 +73,9 @@ export default class GroupPurchase extends Component {
                     renderRow={this._renderRow}
                     renderHeader={this._renderHeader}
                     onEndReached={() => {
-                      if (productList.list.size !== 0) {
-                          this.props.onEndReached && this.props.onEndReached();
-                      }
+                        if (productList && productList.list && productList.list.size !== 0) {
+                            this.props.onEndReached && this.props.onEndReached();
+                        }
                     }}
                 />
             </View>