I am getting an error in my console and cant seem to fix it

//Problem user interaction doesnt provide desired results
//solution- add ineractivity so user can manage daily tasks
var taskInput = document.getElementById("new-task");//new-task
var addButton = document.getElementsByTagName("button")[0]; //first button
var incompleteTaskHolder = document.getElementById("incomplete-tasks"); //incomplete-tasks
var completedTasksHolder = document.getElementById("completed-tasks"); //completed-tasks
//Add a new task
var addTask = function() {
  console.log("Add task...");
  //when button pressed
  //Create a new list item with text from #new-task
    //input checkbox
    //label
    //input text
    //button.edit
    //button.delete
    //each element needs to be modified and appended
}

//Edit an exsisting task
var editTask = function() {
  console.log("Edit task...");
  //when the edit button is pressed
    //if the class of the parent is .editmode
      //Switch from .editmode
      //label text becomes the input value
      //else
        //switch to .editmode
        //input value becomes label text

      //toggle .editmode
}

//Delete exsisiting task
var deleteTask = function() {
  console.log("Delete task...");
  //when delete button is pressed 
   //remove the parent list item from the ul
}

//Mark a task complete
var taskComplete = function() {
  console.log("Complete task...");
  //when the checkbox is checked
   // append the task list item from completed
}

//Mark task as incomplete
var taskIncomplete = function() {
  console.log("Incomplete task...");
  //when the checkbox is unchecked
    //append the task list item to the #incompleted-tasks
}

//changed Taks to Task correct spelling and corrected the references to it in the for loop
var bindTaskEvents = function(taskListItem, checkBoxEventHandler) {
  //changed to console.log
  console.log("Bind list item events");
  //select it's children
  var checkBox = taskListItem.querySelector("input[type=checkbox]");
   var editButton = taskListItem.querySelector("button.edit");
   var deleteButton = taskListItem.querySelector("button.delete");
    //bind editTask to edit button
  editButton.onclick = editTask;
    //bild deleteTask to delete button
  deleteButton.onclick = deleteTask;
    //bind checkBoxEventHandler to check button
  checkBox.onchange = checkBoxEventHandler;
}
//Set the click handeler to the addTask function

addButton.onclick = addTask;

//cycle over incomplete tasks holdermul list items
for(var i = 0; i < incompleteTaskHolder.children.length; i++) {

    //bind events to list items children (taskComplete)
  bindTaskEvents(incompleteTaskHolder.children[i], taskComplete);
}

//cycle over completetasks holdermul list items
//changed completeTaskHolder to completedTasksHolder
for(var i = 0; i < completedTasksHolder.children.length; i++){

    //bind events to list items children (taskIncomplete)
  bindTaskEvents(completedTasksHolder.children[i], taskIncomplete);
}