Make sure that strict_types declaration is always at the very top of the file.

app/Factory/TransactionFactory.php

@@ -1,4 +1,5 @@
 <?php
+declare(strict_types=1);
 /**
  * TransactionFactory.php
  * Copyright (c) 2018 thegrumpydictator@gmail.com
@@ -19,7 +20,6 @@
  * along with Firefly III. If not, see <http://www.gnu.org/licenses/>.
  */
 
-declare(strict_types=1);
 
 namespace FireflyIII\Factory;