message: Check className has a truthy value before trying anything else
diff: @@ -42,7 +42,7 @@ export function arrayKeys<GenericType>(array: GenericType): number[] {
  export function removeClass(node: HTMLElement, className: string): void {
  const cl = node.classList
  - if (cl.contains(className)) cl.remove(className)
  + if (className && cl.contains(className)) cl.remove(className)
  }
  export function addClass(node: HTMLElement, className: string): void {
  