fix: crash while programm start, cause of missing open statement in module-info.java

src/main/java/module-info.java

@@ -10,6 +10,7 @@ module gui {
 
 
     opens de.hdm_stuttgart.battlearena to javafx.fxml;
+    opens de.hdm_stuttgart.battlearena.Controller to javafx.fxml;
     opens de.hdm_stuttgart.battlearena.Model.DataStorage.Classes to com.google.gson;
     opens de.hdm_stuttgart.battlearena.Model.DataStorage.Classes.Exceptions to com.google.gson;
     opens de.hdm_stuttgart.battlearena.Model.DataStorage.Classes.Utilities to com.google.gson;