zero length operations are valid

diff --git a/src/jalview/datamodel/CigarBase.java b/src/jalview/datamodel/CigarBase.java
index 2508717..d351603 100644 (file)
--- a/src/jalview/datamodel/CigarBase.java
+++ b/src/jalview/datamodel/CigarBase.java
@@ -268,10 +268,14 @@ public abstract class CigarBase
     {\r
       throw new Error("Implementation error. Invalid operation string.");\r
     }\r
-    if (range <= 0)\r
+    if (range==0)\r
+    {\r
+      return; // No Operation to add.\r
+    }\r
+    if (range < 0)\r
     {\r
       throw new Error(\r
-              "Invalid range string (must be non-zero positive number)");\r
+              "Invalid range string (must be zero or positive number)");\r
     }\r
     int lngth = 0;\r
     if (operation == null)\r