Uncaught TypeError: Cannot read property 'x' of undefined Collision check. How to solve the problem?

Question

JavaScript

Uncaught TypeError: Cannot read property 'x' of undefined Collision check. How to solve the problem ?
here is the game. The Game itself
Check for clash of swords, with doge.

Game.prototype.update = function(){
  for(let i = 0; i < this.doges.length; i++){
  	for(let i = 0; i < this.sword_right.length; i++){
  		if(Math.abs(this.doges[i].x+50-this.sword_right[i].x)< 50 && Math.abs(this.doges[i].y+-this.sword_right[i].y)<50){
  			this.doges.splice(i,1);
  			break;
  		}
  	}
  }
}

Help me please. Maybe I'm doing the check wrong.