Four in a row Object-Oriented JS challenge [Spaces are not showing & no errors in console]

class Space {
    constructor(x, y) {
        this.x = x;
        this.y = y;
        this.id = `space-${x}-${y}`;
        this.token = null;
        this.diameter = 76;
        this.radius = this.diameter / 2;
    }

    drawSVGSpace() {    
        const svgSpace = document.createElementNS("http://www.w3.org/2000/svg", "circle");
        svgSpace.setAttributeNS(null, "id", this.id);
        svgSpace.setAttributeNS(null, "cx", (this.x * this.diameter) + this.radius);
        svgSpace.setAttributeNS(null, "cy", (this.y * this.diameter) + this.radius);
        svgSpace.setAttributeNS(null, "r", this.radius - 8);
        svgSpace.setAttributeNS(null, "fill", "black");
        svgSpace.setAttributeNS(null, "stroke", "none");

        document.getElementById("mask").appendChild(svgSpace);     
    }
}

class Board {
    constructor() {
        this.row = 6;
        this.column = 7;
        this.spaces = this.createSpaces();
    }

    createSpaces() {
        const spaces = [];

        for(let x = 0; x < this.columns; x++) {
            const column = [];

            for(let y = 0; y < this.rows; y++) {
                const space = new Space(x, y);
                column.push(space);
            }
            spaces.push(column);
        }
        return spaces;
    }

    drawHTMLBoard() {
        for(let column of this.spaces) {
            for(let space of column){
                space.drawSVGSpace();
            }
        }
    }
}