X-Git-Url: http://source.jalview.org/gitweb/?a=blobdiff_plain;f=src%2Fjalview%2Fworkers%2FConservationThread.java;h=571234cb749388a0fe8f2a875301e25aae5918b7;hb=d221d910aad1d44bbc2e0a1f7ac44f5ceb575018;hp=4ada8eac5de5d04a584adc1009448935b66a9126;hpb=c793b702ed3c1ec890411db7156c63dfb3c40153;p=jalview.git

diff --git a/src/jalview/workers/ConservationThread.java b/src/jalview/workers/ConservationThread.java
index 4ada8ea..571234c 100644
--- a/src/jalview/workers/ConservationThread.java
+++ b/src/jalview/workers/ConservationThread.java
@@ -55,7 +55,7 @@ public class ConservationThread extends AlignCalcWorker
     {
       calcMan.notifyStart(this); // updatingConservation = true;
 
-      while (!calcMan.notifyWorking(this))
+      while ((calcMan != null) && (!calcMan.notifyWorking(this)))
       {
         try
         {
@@ -69,7 +69,8 @@ public class ConservationThread extends AlignCalcWorker
           ex.printStackTrace();
         }
       }
-      if (alignViewport.isClosed())
+      if ((alignViewport == null) || (calcMan == null)
+              || (alignViewport.isClosed()))
       {
         abortAndDestroy();
         return;