[bugfix] Avoid IndexOutOfBoundsException

exist-core/src/main/java/org/exist/xquery/value/Type.java

@@ -551,6 +551,8 @@ public static boolean subTypeOf(int subtype, final int supertype) {
      *
      * @param subtype type code of the sub type
      * @return type constant for the super type
+     *
+     * @throws IllegalArgumentException if {@code subtype} has no defined super type
      */
     public static int getSuperType(final int subtype) {
         if (subtype == ITEM || subtype == NODE) {
@@ -559,6 +561,11 @@ public static int getSuperType(final int subtype) {
             return subtype;
         }
 
+        if (subtype >= superTypes.length) {
+            // Note that EMPTY_SEQUENCE is *not* a sub-type of anything else than itself
+            throw new IllegalArgumentException("Type: " + subtype + " has no super types defined");
+        }
+
         final int supertype = superTypes[subtype];
         if (supertype == 0) {
             LOG.warn("eXist-db does not define a super-type for the sub-type {}", getTypeName(subtype), new Throwable());