wallpapper config storage fix

main.js

@@ -1,6 +1,7 @@
 const DEFAULT_USER = "defaultUser";
 const DEFAULT_SESSION = "defaultSession";
 const DEFAULT_WALLPAPPER = "defaultWallpapper";
+const WALLPAPPER_ELEMENT = "wallpappers";
 
 function togglePasswordVisibility() {
   var passwd = document.getElementById("password");
@@ -19,7 +20,7 @@ function updateDefaults(user, session) {
 	localStorage.setItem(DEFAULT_USER, user)
 	localStorage.setItem(DEFAULT_SESSION, session)
 
-	var wallpapper = document.getElementById("wallpappers").value
+	var wallpapper = document.getElementById(WALLPAPPER_ELEMENT).value
 	if(wallpapper) {
 		localStorage.setItem(DEFAULT_WALLPAPPER, wallpapper)
 	}
@@ -106,7 +107,7 @@ function initGreeter() {
 		select.appendChild(btn)
 	}
 
-	const wallpappers = document.getElementById('wallpappers');
+	const wallpappers = document.getElementById(WALLPAPPER_ELEMENT);
 
 	wallpappers.addEventListener('change', (event) => {
 		updateWallpapper(event.target.value);