Bugfix for SampleRenameStep without intervals

Author: bbimber

SequenceAnalysis/src/org/labkey/sequenceanalysis/run/variant/SampleRenameStep.java

@@ -27,6 +27,7 @@
 import java.io.File;
 import java.util.ArrayList;
 import java.util.Arrays;
+import java.util.Collections;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -110,7 +111,7 @@ else if (enforceChangeAll)
             List<Interval> queryIntervals = intervals;
             if (queryIntervals == null || queryIntervals.isEmpty())
             {
-                queryIntervals.add(null);
+                queryIntervals = Collections.singletonList(null);
             }
 
             int i = 0;