Animation fails due to a NullPointerException which I'm certain shouldn't be thrown (LibGDX / Java)

What the title says basically. I’ve been stuck on this error for a few hours I got it to work earlier but I honestly can’t see why its failing now (ctrl + z’d back to the working stage). Here’s my code:

public class Animator {
    private Animation animation;
    private TextureRegion[] walkFrames;
    private TextureRegion[] jumpFrames;
    private TextureRegion[] enemyFrames;
    private Texture jumpSheet;
    private Texture walkSheet;
    private Texture enemySheet;
    private TextureRegion currentFrame;
    private Animation enemyAnimation;
    private Animation jumpAnimation;
    private Animation walkAnimation;
    private TextureRegion[][] animationType;
    private TextureRegion[] animateJump;
    private TextureRegion[] animateWalk;
    private TextureRegion[] animateEnemy;
    private GameObject object;
    private float stateTime;

    public Animator(GameObject object) {
        this.object = object;
        jumpSheet = new Texture(Gdx.files.internal("jumpsheet.png"));
        walkSheet = new Texture(Gdx.files.internal("walksheet.png"));
        enemySheet = new Texture(Gdx.files.internal("enemySheet.png"));
        enemyAnimation = animate(1, 4, enemySheet);
        jumpAnimation = animate(1, 7, jumpSheet);
        walkAnimation = animate(1, 4, walkSheet);
        stateTime = 0f;
    }

    public Animation animate(int rows, int cols, Texture spriteSheet) {
        TextureRegion[] frames = new TextureRegion[cols * rows];
        animationType = TextureRegion.split(spriteSheet, spriteSheet.getWidth()
                / cols, spriteSheet.getHeight() / rows);
        int index = 0;
        for (int i = 0; i < frameRows; i++) {
            for (int j = 0; j < frameCols; j++) {
                frames[index++] = animationType[i][j];
            }
        }
        animation = new Animation(0.25f, frames);
        return animation;
    }

    public void render(SpriteBatch batch) {
        stateTime += Gdx.graphics.getDeltaTime();
        if (object.getType() == ObjectType.PLAYER
                && object.getState() == ObjectState.JUMPING) {
            currentFrame = jumpAnimation.getKeyFrame(stateTime, true);
        } else if (object.getType() == ObjectType.PLAYER
                && object.getState() == ObjectState.NORMAL) {
            currentFrame = walkAnimation.getKeyFrame(stateTime, true);
        } else {
            currentFrame = enemyAnimation.getKeyFrame(stateTime, true);
        }
        batch.draw(currentFrame, object.getxPos(), object.getyPos()); // Null Pointer
    }
}

I get the NullPointer on the last line, and if I run in debug mode with breakpoints it tells me that currentFrame is null (at every stage of the if statement). Can anyone see why?

Any help is highly appreciated, thanks.