seq size cant be less than 2 for tree

diff --git a/src/jalview/gui/AlignFrame.java b/src/jalview/gui/AlignFrame.java
index cc57961..9d1b8f1 100755 (executable)
--- a/src/jalview/gui/AlignFrame.java
+++ b/src/jalview/gui/AlignFrame.java
@@ -2200,6 +2200,9 @@ public class AlignFrame
         return;\r
       }\r
 \r
+      if(viewport.alignment.getHeight()<2)\r
+        return;\r
+\r
       tp = new TreePanel(viewport, type, pwType);\r
     }\r
 \r