Priority queue, please help, i don't know why it doesn't pass last test

JavaScript
1

Here is my code

function PriorityQueue () {
this.collection = [];
this.printCollection = function() {
  console.log(this.collection);
};
// Only change code below this line
this.enqueue = function(item) {
  let i = this.collection.findIndex(iCol => iCol[1] >= item[1])
  if(i < 0) {
    this.collection.push(item)
  } else {
    this.collection.splice(i, 0, item)
  }
}

this.dequeue = function() {
  if(this.isEmpty()) return
  return this.collection.shift()[0]
}

this.front = function() {
  if(this.isEmpty()) return
  return this.collection[0][0]
}

this.size = function() {
  return this.collection.length
}

this.isEmpty = function() {
  return this.collection.length == 0
}
// Only change code above this line
}

const priorityQueue = new PriorityQueue;
priorityQueue.enqueue(["human", 1]);
priorityQueue.enqueue(["ufo", 0]);
priorityQueue.enqueue(["rabbit", 2]);
priorityQueue.enqueue(["ufo2", 0]);
priorityQueue.enqueue(["ufo3", 0]);
priorityQueue.enqueue(["animal", 2]);

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Challenge: Create a Priority Queue Class

Link to the challenge:
https://www.freecodecamp.org/learn/coding-interview-prep/data-structures/create-a-priority-queue-class