Fix/source mangas applied filters lost when triggering search (#741)

* Delete storage item when setting "undefined"

* Preserve source browse filters on search

The set filters were lost in case a search was triggered

src/util/AppStorage.ts

@@ -28,6 +28,7 @@ export class Storage {
 
     setItem(key: string, value: unknown): void {
         if (value === undefined) {
+            this.storage.removeItem(key);
             return;
         }