Remove blank page collection cache (#2033)

* Remove blank page collection cache

* Lint fix (why lol?)

Author: jonathanKingston

injected/src/features/page-context.js

@@ -381,7 +381,7 @@ export default class PageContext extends ContentFeature {
 
     startObserving() {
         this.log.info('Starting observing', this.mutationObserver, this.#cachedContent);
-        if (this.mutationObserver && this.#cachedContent && !this.isObserving) {
+        if (this.mutationObserver && this.#cachedContent && !this.isObserving && document.body) {
             this.isObserving = true;
             this.mutationObserver.observe(document.body, {
                 childList: true,
@@ -445,7 +445,9 @@ export default class PageContext extends ContentFeature {
         }
 
         // Cache the result - setter handles timestamp and observer
-        this.cachedContent = content;
+        if (content.content.length > 0) {
+            this.cachedContent = content;
+        }
         return content;
     }