#vulnerable code 
                                void updateTable(HashSet<IntVar> fdvs) {

        for (IntVar v : fdvs) {

            // recent pruning
            IntDomain cd = v.dom();
            IntDomain pd = cd.previousDomain();
            IntDomain rp;
            int delta;
            if (pd == null) {
                rp = cd;
                delta = IntDomain.MaxInt;
            } else {
                rp = pd.subtract(cd);
                delta = rp.getSize();
                if (delta == 0)
                    continue;
            }

            mask = 0;  // clear mask
            int xIndex = varMap.get(v);

            Map<Integer, Long> xSupport = supports[xIndex];
            if (delta < cd.getSize()) { // incremental update
                ValueEnumeration e = rp.valueEnumeration();
                while (e.hasMoreElements()) {
                    Long bs = xSupport.get(e.nextElement());
                    if (bs != null)
                        mask |= (bs.longValue());
                }
                mask = ~mask;
            } else { // reset-based update
                ValueEnumeration e = cd.valueEnumeration();
                while (e.hasMoreElements()) {
                    Long bs = xSupport.get(e.nextElement());
                    if (bs != null)
                        mask |= (bs.longValue());
                }
            }

            boolean empty = intersectWithMask();
            if (empty)
                throw store.failException;
        }
    } 
                            #location 21 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                boolean validTuple(int index) {

        int[] t = tuple[index];
        int n = t.length;
        int i = 0;
        while (i < n) {
            if (!x[i].dom().contains(t[i]))
                return false;
            i++;
        }
        return true;
    }