What is “illegal invocation” error that stops my program from working?

I was developing a program in JavaScript, when each time the button is pressed the image should alternate on each press- if it is currently the “box open” image, it should switch to the “box closed” image.Similarly, if it is currently on closed, it should witch to the “box open”. I am however facing an “illegal invocation” error How can this be solves?

var jackbox = document.getElementById("jackbox");                                               
                                                
  function click()                                              
  {                                             
    if (this.id == "Jump out,Jack!")                                                
    {                                               
      document.getElementById("jackbox").src = "https://www.paulneve.com/pp/jackbox-open.jpg";                                              
                                                
    }                                               
    else(this.id == "Jump out,Jack")                                                
    {                                               
      document.getElementById("jackbox").src = "https://www.paulneve.com/pp/jackbox-open.jpg";                                              
                                                
    }                                               
                                                
  }                                             
                                                
document.getElementById("toggle").onclick = open;

<div style="text-align: center; height: 280px;">
    <img id="jackbox" src="https://www.paulneve.com/pp/jackbox-closed.jpg" />
    <br/>
    <button id="toggle">Jump out, Jack!</button>
</div>