let elt = !!e
? e.target
: document.getElementById("btn" + letter.toUpperCase() + type);
+ // WARNING: this method is called at created in a setTimeout:
+ // => the page could have changed and element no longer defined.
+ if (!elt)
+ return;
elt.classList.add("active");
if (!!elt.previousElementSibling)
elt.previousElementSibling.classList.remove("active");