Fix 2nd client crashing on trying to join a server via localhost

Removes unnecessary and too early registration step and fixes a whitelist issue

Author: Cervator

engine/src/main/java/org/terasology/engine/core/modes/StateLoading.java

@@ -173,9 +173,6 @@ private void initClient(GameEngine engine, ServiceRegistry serviceRegistry) {
 //        loadProcesses.add(new ProcessBlockPrefabs(context));
         loadProcesses.add(new LoadExtraBlockData(serviceRegistry));
         loadProcesses.add(new InitialiseComponentSystemManager(serviceRegistry));
-        if (!headless) {
-            loadProcesses.add(new RegisterInputSystem(context));
-        }
 //        loadProcesses.add(new RegisterSystems(context, netMode));
 //        loadProcesses.add(new RegisterWorldSystems(gameManifest, context));
         loadProcesses.add(new InitialiseCommandSystem(serviceRegistry));

engine/src/main/java/org/terasology/engine/core/module/ExternalApiWhitelist.java

@@ -56,6 +56,8 @@ public final class ExternalApiWhitelist {
     public static final Set<String> PACKAGES = new ImmutableSet.Builder<String>()
             .addAll(NUI_PACKAGES)
             .addAll(GESTALT_ECS_PACKAGES)
+            // Allow persistence internals needed during client join (EntityRestorer, etc.)
+            .add("org.terasology.engine.persistence.internal")
             .add("org.terasology.math")
             .add("org.terasology.math.geom")
             .add("org.terasology.joml.geom")