TypeError: e is undefined

JavaScript
1 
<script>
 $(document).ready(function(){

 });
</script>
<div class="container-fluid">
  <h3 class="text-primary text-center">jQuery Playground</h3>
  <div class="row">
    <div class="col-xs-6">
      <h4>#left-well</h4>
      <div class="well" id="left-well">
        <button class="btn btn-default target" id="target1">#target1</button>
        <button class="btn btn-default target" id="target2">#target2</button>
        <button class="btn btn-default target" id="target3">#target3</button>
      </div>
    </div>
    <div class="col-xs-6">
      <h4>#right-well</h4>
      <div class="well" id="right-well">
        <button class="btn btn-default target" id="target4">#target4</button>
        <button class="btn btn-default target" id="target5">#target5</button>
        <button class="btn btn-default target" id="target6">#target6</button>
      </div>
    </div>
  </div>
</div>



<script>
$(document).ready(function(){

});
</script>
<div class="container-fluid">
 <h3 class="text-primary text-center">jQuery Playground</h3>
 <div class="row">
   <div class="col-xs-6">
     <h4>#left-well</h4>
     <div class="well" id="left-well">
       <button class="btn btn-default target" id="target1">#target1</button>
       <button class="btn btn-default target" id="target2">#target2</button>
       <button class="btn btn-default target" id="target3">#target3</button>
     </div>
   </div>
   <div class="col-xs-6">
     <h4>#right-well</h4>
     <div class="well" id="right-well">
       <button class="btn btn-default target" id="target4">#target4</button>
       <button class="btn btn-default target" id="target5">#target5</button>
       <button class="btn btn-default target" id="target6">#target6</button>
     </div>
   </div>
 </div>
</div>

Your browser information:

User Agent is: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:78.0) Gecko/20100101 Firefox/78.0.

Challenge: Learn How Script Tags and Document Ready Work

Link to the challenge:

2

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