chore: Fix linting issues (#546)

src/embed.ts

@@ -484,7 +484,7 @@ class Embed extends LitElement {
       return;
     }
 
-    if (win?.customElements.get(this.mainElementName)) {
+    if (win.customElements.get(this.mainElementName)) {
       this.mainElement = doc.querySelector(this.mainElementName);
       return;
     }

src/pages.ts

@@ -424,6 +424,7 @@ class Pages extends LitElement {
     let buf = "";
 
     let next = reader.read();
+    // eslint-disable-next-line @typescript-eslint/no-unnecessary-condition -- Expected true
     while (true) {
       const { done, value } = await next;