fix formatting of combat zones

EliteBGS/LogGenerator/CombatZoneFormat.cs

@@ -22,11 +22,18 @@ class CombatZoneFormat : LogFormatter {
             int optionals = log.Value
                                 .Sum(x => x.OptionalObjectivesCompleted)
                                 ;
-            builder.AppendFormat("Won {0}x {1} {2} Combat Zone(s)",
-                log.Value.Count, 
-                log.Key.Grade,
-                log.Key.Type
-                );
+            if (!string.IsNullOrEmpty(log.Key.Grade)) {
+                builder.AppendFormat("Won {0}x {1} {2} Combat Zone(s)",
+                    log.Value.Count,
+                    log.Key.Grade,
+                    log.Key.Type
+                    );
+            } else {
+                builder.AppendFormat("Won {0}x {1} Combat Zone(s)",
+                    log.Value.Count,
+                    log.Key.Type
+                    );
+            }
 
             if (optionals > 0) {
                 builder.AppendFormat(" (with {0} optional objectives)", optionals);