Meta browser can happen NPE when the server or target server of region is null

Reproduction Steps:

1. We create a new table with many regions , for example: 

//代码占位符
create 't01' , 'info' , SPLITS => Array(1..999).map{|e|e.to_s}

2. At the same time, we scan meta entries of this table on meta browser by hbase UI

3. We would get NPE if those regions is initializing and the server or target server is null