referencer.js(7,22): error TS18048: 'p.x' is possibly 'undefined'.
referencer.js(7,33): error TS18048: 'p.y' is possibly 'undefined'.


==== source.js (0 errors) ====
    /**
     * @param {number} x
     * @param {number} y
     */
    export function Point(x, y) {
        if (!(this instanceof Point)) {
            return new Point(x, y);
        }
        this.x = x;
        this.y = y;
    }
    
==== referencer.js (2 errors) ====
    import {Point} from "./source";
    
    /**
     * @param {Point} p
     */
    export function magnitude(p) {
        return Math.sqrt(p.x ** 2 + p.y ** 2);
                         ~~~
!!! error TS18048: 'p.x' is possibly 'undefined'.
                                    ~~~
!!! error TS18048: 'p.y' is possibly 'undefined'.
    }
    