what is an uncaught type error code example

Example 1: what is an uncaught type error

update() {
    var lSpritesLength=this.sprites.length;

        for(let i=0;i<lSpritesLength;i++){

            this.sprites[i].update();
        }
  }

Example 2: what is an uncaught type error

update() {
    var lSpritesLength=this.sprites.length;

        for(let i=0;i<lSpritesLength;i++){

            this.sprites[i].update();
        }
  }