#vulnerable code 
                                public void train(final Access1D<Double> givenInput, final Access1D<Double> targetOutput) {

        Access1D<Double> current = this.invoke(givenInput);

        myGradients[0].fillMatching(givenInput);
        myGradients[myGradients.length - 1].fillMatching(targetOutput, myError.getDerivative(), current);

        for (int k = this.depth() - 1; k >= 0; k--) {

            CalculationLayer layer = this.getLayer(k);

            Access1D<Double> input = k == 0 ? givenInput : this.getOutput(k - 1);
            Primitive64Store output = this.getOutput(k);

            Primitive64Store upstreamGradient = myGradients[k];
            Primitive64Store downstreamGradient = myGradients[k + 1];

            layer.adjust(input, downstreamGradient, -myLearningRate, upstreamGradient, output);
        }
    } 
                            #location 6 
                            #vulnerability type NULL_DEREFERENCE
#fixed code
                                public void train(final Access1D<Double> givenInput, final Access1D<Double> targetOutput) {

        Access1D<Double> current = this.invoke(givenInput);

        myGradients[0].fillMatching(givenInput);
        myGradients[myGradients.length - 1].fillMatching(targetOutput, myError.getDerivative(), current);

        for (int k = this.depth() - 1; k >= 0; k--) {

            CalculationLayer layer = this.getLayer(k);

            Access1D<Double> input = k == 0 ? givenInput : this.getOutput(k - 1);
            PhysicalStore<Double> output = this.getOutput(k);

            PhysicalStore<Double> upstreamGradient = myGradients[k];
            PhysicalStore<Double> downstreamGradient = myGradients[k + 1];

            layer.adjust(input, downstreamGradient, -myLearningRate, upstreamGradient, output);
        }
    }