diff --git a/src/SEQTA.ts b/src/SEQTA.ts
index de3586f5..8c3b0bb0 100644
--- a/src/SEQTA.ts
+++ b/src/SEQTA.ts
@@ -859,25 +859,29 @@ async function CheckLoadOnPeriods() {
 }
 
 export function closeSettings() {
-  var extensionsettings = document.getElementById('ExtensionPopup');
+  const ExtensionSettings = document.getElementById('ExtensionPopup')!;
+  const ExtensionIframe = document.getElementById('ExtensionIframe') as HTMLIFrameElement;
 
   if (SettingsClicked == true) {
-    extensionsettings.classList.add('hide');
+    ExtensionSettings.classList.add('hide');
     animate(
       '#ExtensionPopup',
       { opacity: [1, 0], scale: [1, 0] },
       { easing: spring({ stiffness: 220, damping: 18 }) }
     );
     SettingsClicked = false;
-    document.getElementById('ExtensionIframe').contentWindow.postMessage('popupClosed', '*');
+
+    if (ExtensionIframe.contentWindow) {
+      ExtensionIframe.contentWindow.postMessage('popupClosed', '*');
+    }
   }
 
-  extensionsettings.classList.add('hide');
+  ExtensionSettings.classList.add('hide');
 }
 
 function addExtensionSettings() {
   const link = GetCSSElement('interface/popup.css');
-  document.querySelector('html').appendChild(link);
+  document.querySelector('html')!.appendChild(link);
 
   const extensionPopup = document.createElement('div');
   extensionPopup.classList.add('outside-container', 'hide');
@@ -887,23 +891,27 @@ function addExtensionSettings() {
   const extensionIframe = document.createElement('iframe');
   extensionIframe.src = `${browser.runtime.getURL('interface/index.html')}#settings/embedded`;
   extensionIframe.id = 'ExtensionIframe';
-  extensionIframe.allowTransparency = true;
+  extensionIframe.setAttribute('allowTransparency', 'true');
+  extensionIframe.setAttribute('excludeDarkCheck', 'true');
   extensionIframe.style.width = '384px';
   extensionIframe.style.height = '600px';
   extensionIframe.style.border = 'none';
-  extensionIframe.setAttribute('excludeDarkCheck', true);
   extensionPopup.appendChild(extensionIframe);
 
   const container = document.getElementById('container');
   
   const closeExtensionPopup = () => {
+    const ExtensionIframe = document.getElementById('ExtensionIframe') as HTMLIFrameElement;
+
     extensionPopup.classList.add('hide');
     animate(
       '#ExtensionPopup',
       { opacity: [1, 0], scale: [1, 0] },
       { easing: [.22, .03, .26, 1] }
     );
-    document.getElementById('ExtensionIframe').contentWindow.postMessage('popupClosed', '*');
+    if (ExtensionIframe.contentWindow) {
+      ExtensionIframe.contentWindow.postMessage('popupClosed', '*');
+    }
     SettingsClicked = false;
   };