Phaser 3 Tetris clone, Game freezes when trying to stack blocks

In the Tetris clone I'm making, I'm only working with single blocks right now and I have been trying to stack blocks in a few rows. Here is the code for the blocks

if (this.active == false){
    this.cube = Math.floor((Math.random()* 7));
    this.testblock = this.physics.add.sprite(608, 32, this.blocks[this.cube]);
    this.testblock.body.immovable = true;
    this.testblock.body.allowGravity = false;
    //this.testblock.body.setGravityY(-100);
    this.physics.add.collider(this.walls, this.testblock);
    this.physics.add.collider(this.p1, this.testblock);
    this.activeBlock = this.testblock;
    this.active = true;
}

this.activeBlock.y = this.activeBlock.y + 0.5;

if(Phaser.Input.Keyboard.JustDown(this.keyE)){
    console.log(this.activeBlock.y);
}

if(Phaser.Input.Keyboard.JustDown(this.keyA) && this.activeBlock.x != 352) {
    this.activeBlock.x = this.activeBlock.x - 64;
}

if(Phaser.Input.Keyboard.JustDown(this.keyD) && this.activeBlock.x != 928) {
    this.activeBlock.x = this.activeBlock.x + 64;
}

if (this.activeBlock.y == 416){
    if(this.activeBlock.x == 352 && this.row4[0] != null){
        this.row5[0] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 416 && this.row4[1] != null){
        this.row5[1] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 480 && this.row4[2] != null){
        this.row5[2] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 544 && this.row4[3] != null){
        this.row5[3] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 608 && this.row4[4] != null){
        this.row5[4] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 672 && this.row4[5] != null){
        this.row5[5] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 736 && this.row4[6] != null){
        this.row5[6] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 800 && this.row4[7] != null){
        this.row5[7] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 864 && this.row4[8] != null){
        this.row5[8] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 928 && this.row4[9] != null){
        this.row5[9] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
}


if (this.activeBlock.y == 480){
    if(this.activeBlock.x == 352 && this.row3[0] != null){
        this.row4[0] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 416 && this.row3[1] != null){
        this.row4[1] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 480 && this.row3[2] != null){
        this.row4[2] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 544 && this.row3[3] != null){
        this.row4[3] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 608 && this.row3[4] != null){
        this.row4[4] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 672 && this.row3[5] != null){
        this.row4[5] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 736 && this.row3[6] != null){
        this.row4[6] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 800 && this.row3[7] != null){
        this.row4[7] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 864 && this.row3[8] != null){
        this.row4[8] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 928 && this.row3[9] != null){
        this.row4[9] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
}

if (this.activeBlock.y == 544){
    if(this.activeBlock.x == 352 && this.row2[0] != null){
        this.row3[0] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 416 && this.row2[1] != null){
        this.row3[1] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 480 && this.row2[2] != null){
        this.row3[2] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 544 && this.row2[3] != null){
        this.row3[3] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 608 && this.row2[4] != null){
        this.row3[4] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 672 && this.row2[5] != null){
        this.row3[5] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 736 && this.row2[6] != null){
        this.row3[6] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 800 && this.row2[7] != null){
        this.row3[7] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 864 && this.row2[8] != null){
        this.row3[8] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 928 && this.row2[9] != null){
        this.row3[9] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
}

if (this.activeBlock.y == 608){
    if(this.activeBlock.x == 352 && this.row1[0] != null){
        this.row2[0] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 416 && this.row1[1] != null){
        this.row2[1] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 480 && this.row1[2] != null){
        this.row2[2] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 544 && this.row1[3] != null){
        this.row2[3] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 608 && this.row1[4] != null){
        this.row2[4] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 672 && this.row1[5] != null){
        this.row2[5] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 736 && this.row1[6] != null){
        this.row2[6] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 800 && this.row1[7] != null){
        this.row2[7] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 864 && this.row1[8] != null){
        this.row2[8] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 928 && this.row1[9] != null){
        this.row2[9] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
}

if (this.activeBlock.y == 672){
    if(this.activeBlock.x == 352){
        this.row1[0] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 416){
        this.row1[1] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 480){
        this.row1[2] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 544){
        this.row1[3] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 608){
        this.row1[4] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 672){
        this.row1[5] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 736){
        this.row1[6] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 800){
        this.row1[7] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 864){
        this.row1[8] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
    else if(this.activeBlock.x == 928){
        this.row1[9] = this.activeBlock;
        this.activeBlock = null;
        this.active = false;
    }
}

I've only programmed these first five rows for testing. The first block is landing just fine, but the game freezes when the second block lands. When checking inspection mode, the error message reads Cannot read properties of null (reading 'y') and for some reason the line that triggers it is

if (this.activeBlock.y == 672)

This is supposed to trigger the landing process of the first row, which already has a block in its space at that point. It's as if the line that triggers the landing process of the second row is never triggered.

I'm certain the block passes over the y coordinate, 608, that triggers landing in the second row. And I'm pretty sure nothing is setting the active block to null again along the way. Can someone tell where things went wrong?