message: Fix error message in target path when className not a string
diff: @@ -20,7 +20,7 @@ function elemName(elem: HTMLElement): string {
  s.push(elem.id);
  }
  - if (elem.className) {
  + if (typeof elem.className === 'string') {
  s.push('.');
  s.push(elem.className.split(' ').join('.'));
  }
  