Changed ServiceManager missing service handling

api/src/main/java/fr/atlasworld/network/api/services/ServiceManager.java

@@ -23,5 +23,5 @@ public interface ServiceManager {
      * @param serviceClass parent service class.
      * @return return the registered service, null if no service we're registered with this class.
      */
-    @Nullable <T extends Service> T getService(Class<T> serviceClass);
+    <T extends Service> T getService(Class<T> serviceClass);
 }

api/src/main/java/fr/atlasworld/network/api/services/exception/MissingServiceException.java

@@ -0,0 +1,16 @@
+package fr.atlasworld.network.api.services.exception;
+
+public class MissingServiceException extends RuntimeException {
+
+    public MissingServiceException(String message) {
+        super(message);
+    }
+
+    public MissingServiceException(String message, Throwable cause) {
+        super(message, cause);
+    }
+
+    public MissingServiceException(Throwable cause) {
+        super(cause);
+    }
+}

src/main/java/fr/atlasworld/network/core/services/SystemServiceManager.java

@@ -3,6 +3,7 @@
 import fr.atlasworld.network.api.module.Module;
 import fr.atlasworld.network.api.services.Service;
 import fr.atlasworld.network.api.services.ServiceManager;
+import fr.atlasworld.network.api.services.exception.MissingServiceException;
 import org.jetbrains.annotations.Nullable;
 
 import java.util.Map;
@@ -29,7 +30,7 @@ public <T extends Service> void registerService(Module module, Class<T> serviceC
     @SuppressWarnings("unchecked")
     public <T extends Service> @Nullable T getService(Class<T> serviceClass) {
         if (!this.registeredServices.containsKey(serviceClass))
-            return null;
+            throw new MissingServiceException("No services registered for '" + serviceClass.getName() + "'!");
 
         return (T) this.registeredServices.get(serviceClass);
     }