message: Check files uploaded by user
diff: @@ -98,8 +98,11 @@ function Utils(errorOutputId) { // eslint-disable-line no-unused-vars
  this.addFileInputHandler = function(fileInputId, canvasId) {
  let inputElement = document.getElementById(fileInputId);
  inputElement.addEventListener('change', (e) => {
  - let imgUrl = URL.createObjectURL(e.target.files[0]);
  + let files = e.target.files;
  + if (files.length > 0) {
  + let imgUrl = URL.createObjectURL(files[0]);
  self.loadImageToCanvas(imgUrl, canvasId);
  + }
  }, false);
  };
  