Change EventHandler to always pass by reference and kill return-value semantics.

src/EventHandler.php

@@ -13,5 +13,5 @@ interface EventHandler
      * the next handler is called. Otherwise, return null. Any changes made will be propogated
      * to the event publisher as well.
      */
-    public static function handleEvent(string $event, array $context);
+    public static function handleEvent(string $event, array &$context);
 }

src/EventManager.php

@@ -47,9 +47,6 @@ class EventManager
             if (preg_match($s->getPattern(), $event)) {
                 $class = $s->getClass();
                 $c = $class::handleEvent($event, $context);
-                if ($c !== null) {
-                    $context = $c;
-                }
             }
         }
     }

tests/EventManagerTest.php

@@ -19,7 +19,7 @@ class EventManagerTestInvalidSubscriber
 
 class EventManagerTestSubscriber implements EventHandler
 {
-    public static function handleEvent(string $event, array $context) {}
+    public static function handleEvent(string $event, array &$context) {}
 }
 
 class EventManagerTest extends ModelTestCase

tests/FakeModule/Module.php

@@ -6,7 +6,7 @@ use LotGD\Core\Game;
 use LotGD\Core\Module as ModuleBase;
 
 class Module implements ModuleBase {
-    public static function handleEvent(string $event, array $context) {
+    public static function handleEvent(string $event, array &$context) {
         $context['foo'] = 'baz';
         return $context;
     }