增加接口无数据时保护。review by 孙凯。

@@ -66,11 +66,11 @@ class TalentRank extends Component {
             <RankBody
               monthRank={true}
               fetchNextPage={this._fetchNextPage}
-              dataSource={monthRankData.get('rankList').get('list')}
+              dataSource={(monthRankData && monthRankData.get('rankList')) ? monthRankData.get('rankList').get('list') : []}
               style={styles.container}/>
             <RankBody
               fetchNextPage={this._fetchNextPage}
-              dataSource={totalRankData.get('rankList').get('list')}
+              dataSource={(totalRankData && totalRankData.get('rankList')) ? totalRankData.get('rankList').get('list') : []}
               style={styles.container}/>
         </ScrollView>
       </View>