Convert Sets to Arrays before saving locally (#383)

src/electron/services/electronStorage.service.ts

@@ -39,6 +39,9 @@ export class ElectronStorageService implements StorageService {
     }
 
     save(key: string, obj: any): Promise<any> {
+        if (obj instanceof Set) {
+            obj = Array.from(obj);
+        }
         this.store.set(key, obj);
         return Promise.resolve();
     }