anchor.diff:                </script>
               <% end %>
               <div class="row handin-row">
  +              <div class="error file-error" id="flash_error" style="background: white;display: none;">
  +                There was an error processing your file, please try adding it again.
  +              </div>
                 <div class="valign-wrapper drag-drop-handin" onclick="clickDrag();" ondrop="dropHandler(event);" ondragover="dragOverHandler(event);" ondragenter="dragEnter(event);" ondragexit="dragExit(event);">
                   <p class="center-align" style="color:grey;" ondrop="dropHandler(event);" ondragover="dragOverHandler(event);" ondragenter="dragEnter(event);" ondragexit="dragExit(event);"><b>Drag a file here to hand in. Click to select a file.</b> <br /> <span style="font-size: 10px;">Files do not submit automatically.</span></p>
                 </div>
  
positive.code:                 var submittedFile = false;
  
                  function flashError(message) {
                    const elem = $("<div />").prop("id", "flash_error").addClass("error").text(message);
                    $("#flashes").append(
                      elem
                    );
  
                    setTimeout(() => {
                      elem.hide(500);
                    }, 3000);
                  }
  
                  function dropHandler(e) {
  
negative.code:                   }
  
                    if (fileSelector.files.length === 1) {
                        $(".handin-row").hide(0, function () {
                          $(".file-error").hide();
                        });
                        $(".handedin-row").show();
                        enableSubmit();
                    }
  