Originally I had it as, the error was that c was undefined.
constructor(c){
this.x = c.x || 0;
this.y = c.y || 0;
...
}
I tried doing this as well (as suggested by the answer to this question), the error is that the values always get set to default.
constructor({
x = 0,
y = 0
} = {}){
this.x = x;
this.y = y;
...
}