diff --git a/psalm.xml b/psalm.xml
index 8be3a1d..424fc7d 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -1,6 +1,6 @@
 <?xml version="1.0"?>
 <psalm
-    errorLevel="4"
+    errorLevel="3"
     resolveFromConfigFile="true"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xmlns="https://getpsalm.org/schema/config"
diff --git a/src/Domain/GameGenerator/RandomGameGenerator.php b/src/Domain/GameGenerator/RandomGameGenerator.php
index 1af8d91..ee7ec04 100644
--- a/src/Domain/GameGenerator/RandomGameGenerator.php
+++ b/src/Domain/GameGenerator/RandomGameGenerator.php
@@ -32,6 +32,7 @@ public function __invoke(): Game
         $crime = Crime::CAKE;
         $gameWithOnlyOneSolution = false;
         $lastNumberOfSolutions = 9999999999999;
+        $game = null;
         while (!$gameWithOnlyOneSolution) {
             $rule = $this->randomRule();
             $game = new Game(array_merge($rules, [$rule]), $crime);
@@ -56,6 +57,10 @@ public function __invoke(): Game
                 echo $exception->getMessage() . PHP_EOL;
             }
         }
+
+        if ($game === null) {
+            throw new \LogicException('This should not happen');
+        }
         echo 'Se ha conseguido crear un juego! ' . PHP_EOL;
         return $game;
     }
@@ -83,8 +88,12 @@ private function randomRule(): Rule
 
     private function randomDogAcrossToDogRule(string $className): TwoDogPlaced
     {
+        if (!is_subclass_of($className, TwoDogPlaced::class)) {
+            throw new \InvalidArgumentException("$className must be a subclass of TwoDogPlaced");
+        }
         $firstDogDefinition = $this->randomDogDefinition();
         $secondDogDefinition = $this->randomDogDefinition();
+
         return new $className(
             'El perro %s está enfrente del perro %s',
             $firstDogDefinition,