Exception in thread "DiabloMiner GetWorkAsync for 127.0.0.1" java.lang.NullPointerException
at com.diablominer.DiabloMiner.DiabloMiner$NetworkState.doJSONRPC(DiabloMiner.java:684)
There is a missing null check on xRollNTime at line 681. Just make it look like the following:
if(xRollNTime != null && !"n".equalsIgnoreCase(xRollNTime)) {