Fix sw error

static/CustomSW.js

@@ -9,12 +9,12 @@ const closePwaDialogBtn = document.querySelector('#closePwaDialog')
 // functions
 function showCustomInstallPromotion() {
 	setTimeout(function() {
-		customDialog.classList.add('active')
+		customDialog?.classList.add('active')
 	}, 500)
 }
 function hideCustomInstallPromotion() {
 	setTimeout(function() {
-		customDialog.classList.remove('active')
+		customDialog?.classList.remove('active')
 	}, 500)
 }
 
@@ -30,11 +30,11 @@ window.addEventListener('beforeinstallprompt', e => {
 })
 
 events.forEach(evt => {
-	closePwaDialogBtn.addEventListener(evt, e => {
+	closePwaDialogBtn?.addEventListener(evt, e => {
 		hideCustomInstallPromotion()
 	})
 
-	installBtn.addEventListener(evt, e => {
+	installBtn?.addEventListener(evt, e => {
 		// Hide the app provided install promotion
 		hideCustomInstallPromotion()
 		// Show the install prompt
@@ -50,7 +50,7 @@ events.forEach(evt => {
 	})
 
 	try {
-		showPwaDialogBtn.addEventListener(evt, e => {
+		showPwaDialogBtn?.addEventListener(evt, e => {
 			if (deferredPrompt) {
 				showCustomInstallPromotion()
 			} else {