How do you prevent player from jumping up walls using the matter physics engine with a tilemap in Phaser 3

Question

Im trying to create a platformer game in phaser 3 using the matter physics engine, currently im trying to create levels using tiled, I have gotten to a point where the player can't infinitely jump however they can still jump up walls.

Im currently trying to make it so they can only jump if they are colliding with a specific layer called floor.

When I try to use the code below I get an error saying:

Uncaught TypeError: Cannot set properties of null (setting 'label')

game.js (create function):

create() {

    //External function to create player
    player(this,'test',300,200,'player')
    pawn.setScale(1.5)
    pawn.setDepth(2)
    pawn.setBounce(0.1)
    pawn.setFriction(0,0,1)
    pawn.setCircle(20)
    pawn.setMass(1)

    this.touchingGround = false;

    this.jumpForce = 0.05

    this.map = this.make.tilemap({key: 'lv3'})
    this.tileset = this.map.addTilesetImage('tiles','tile', 32, 32)

    this.walls = this.map.createLayer('walls', this.tileset)
    this.walls.setCollisionByExclusion(-1, true);

    this.floor = this.map.createLayer('floor', this.tileset)
    this.floor.setCollisionByExclusion(-1, true);

    this.matter.world.convertTilemapLayer(this.walls);
    this.matter.world.convertTilemapLayer(this.floor);



     pawn.body.label = 'player'
     this.floor.body.label = 'floor'

     
    this.matter.world.on("collisionactive", (e,o1, o2) => {
        if(o1.label == 'player' && o2.label == 'floor')
        {
            this.touchingGround = true;
        }
    });

};

Sorry if this is a really easy fix or just doesn't work and I'm being stupid.