Fix phpstan issues.

app/Api/V1/Controllers/Chart/AccountController.php

@@ -98,7 +98,7 @@ class AccountController extends Controller
         $frontPage  = app('preferences')->get('frontPageAccounts', $defaultSet);
         $default    = app('amount')->getDefaultCurrency();
 
-        if (empty($frontPage->data)) {
+        if (!(is_array($frontPage->data) && count($frontPage->data) > 0)) {
             $frontPage->data = $defaultSet;
             $frontPage->save();
         }

app/Api/V1/Controllers/Data/PurgeController.php

@@ -19,6 +19,8 @@
  * along with this program.  If not, see <https://www.gnu.org/licenses/>.
  */
 
+declare(strict_types=1);
+
 namespace FireflyIII\Api\V1\Controllers\Data;
 
 use FireflyIII\Api\V1\Controllers\Controller;

app/Api/V1/Requests/Data/Bulk/TransactionRequest.php

@@ -62,7 +62,7 @@ class TransactionRequest extends FormRequest
     }
 
     /**
-     * @return string[]
+     * @return array
      */
     public function rules(): array
     {

app/Api/V1/Requests/Models/Account/UpdateRequest.php

@@ -101,6 +101,7 @@ class UpdateRequest extends FormRequest
      */
     public function rules(): array
     {
+        /** @var Account $account */
         $account        = $this->route()->parameter('account');
         $accountRoles   = implode(',', config('firefly.accountRoles'));
         $types          = implode(',', array_keys(config('firefly.subTitlesByIdentifier')));