JAL-3763 failsafe check for null

diff --git a/src/jalview/datamodel/AlignedCodonFrame.java b/src/jalview/datamodel/AlignedCodonFrame.java
index d59078b..5240f0c 100644 (file)
--- a/src/jalview/datamodel/AlignedCodonFrame.java
+++ b/src/jalview/datamodel/AlignedCodonFrame.java
@@ -170,6 +170,10 @@ public class AlignedCodonFrame
       int[] codon = null;
       SequenceI mappedSeq = null;
       SequenceI ds = seq.getDatasetSequence();
+      if (ds == null)
+      {
+        ds = seq;
+      }
       
       if (this.fromSeq == seq || this.fromSeq == ds)
       {