TestSupportVehicle: Prevent error when grounded for Fixed Wing type c…

…hecking

megamek/src/megamek/common/verifier/TestSupportVehicle.java

@@ -84,14 +84,18 @@ static Set<SVType> allBut(SVType first, SVType... rest) {
         }
 
         /**
-         * Finds the enum value corresponding to a support vehicle based on movement mode.
+         * Finds the enum value corresponding to a support vehicle.
          *
          * @param entity The support vehicle
          * @return       The support vehicle type, or {@code null} if the entity's movement type is not
          *               a valid one for a support vehicle.
          */
         public static @Nullable
         SVType getVehicleType(Entity entity) {
+            // When grounded, FWS revert to wheeled movement mode; must be independent of this
+            if (entity instanceof FixedWingSupport) {
+                return FIXED_WING;
+            }
             switch (entity.getMovementMode()) {
                 case AIRSHIP:
                     return AIRSHIP;