All: Attempt to fix all known bugs.

src/main/java/io/github/edwinmindcraft/calio/client/CalioClientEventHandler.java

@@ -2,8 +2,10 @@
 
 import io.github.apace100.calio.resource.OrderedResourceListenerManager;
 import io.github.edwinmindcraft.calio.api.CalioAPI;
+import io.github.edwinmindcraft.calio.common.registry.CalioDynamicRegistryManager;
 import net.minecraft.server.packs.PackType;
 import net.minecraftforge.api.distmarker.Dist;
+import net.minecraftforge.client.event.ClientPlayerNetworkEvent;
 import net.minecraftforge.client.event.RegisterClientReloadListenersEvent;
 import net.minecraftforge.eventbus.api.SubscribeEvent;
 import net.minecraftforge.fml.common.Mod;
@@ -14,4 +16,9 @@ public class CalioClientEventHandler {
  public void addClientResources(RegisterClientReloadListenersEvent event) {
  OrderedResourceListenerManager.getInstance().addResources(PackType.CLIENT_RESOURCES, event::registerReloadListener);
  }
+
+ @SubscribeEvent
+ public void onDisconnecting(ClientPlayerNetworkEvent.LoggingOut event) {
+ CalioDynamicRegistryManager.removeClientInstance();
+ }
 }

src/main/java/io/github/edwinmindcraft/calio/client/util/ClientHelper.java

@@ -2,14 +2,18 @@
 
 import net.minecraft.client.Minecraft;
 import net.minecraft.core.RegistryAccess;
+import net.minecraftforge.server.ServerLifecycleHooks;
 import org.jetbrains.annotations.Nullable;
 
 public class ClientHelper {
 
  public static boolean isServerContext(@Nullable RegistryAccess access) {
  Minecraft instance = Minecraft.getInstance();
+ //This is wrong in a data context, and annotations are busted;
+ //noinspection ConstantConditions
  if (instance == null) return true; // Data Context
  if (instance.getConnection() == null) return true; // Outside a world
+ if (ServerLifecycleHooks.getCurrentServer() == null) return false; // No server.
  return access != null && access != instance.getConnection().registryAccess();
  }
 }

src/main/java/io/github/edwinmindcraft/calio/common/CalioEventHandler.java

@@ -48,7 +48,7 @@ public static void onServerReload(AddReloadListenerEvent event) {
  @SubscribeEvent
  public static void onServerStopped(ServerStoppedEvent event) {
  CalioAPI.LOGGER.info("Removing Dynamic Registries for: " + event.getServer());
- CalioDynamicRegistryManager.removeInstance(event.getServer().registryAccess());
+ CalioDynamicRegistryManager.removeServerInstance();
  }
 
  @SubscribeEvent

src/main/java/io/github/edwinmindcraft/calio/common/registry/CalioDynamicRegistryManager.java

@@ -29,13 +29,9 @@
 import net.minecraft.server.packs.resources.ResourceManager;
 import net.minecraft.util.GsonHelper;
 import net.minecraft.util.profiling.ProfilerFiller;
-import net.minecraftforge.api.distmarker.Dist;
-import net.minecraftforge.api.distmarker.OnlyIn;
 import net.minecraftforge.common.MinecraftForge;
 import net.minecraftforge.fml.DistExecutor;
-import net.minecraftforge.fml.ModList;
 import net.minecraftforge.fml.ModLoader;
-import net.minecraftforge.fml.javafmlmod.FMLJavaModLoadingContext;
 import net.minecraftforge.network.PacketDistributor;
 import org.apache.commons.lang3.Validate;
 import org.apache.commons.lang3.tuple.Pair;
@@ -59,8 +55,6 @@
 public class CalioDynamicRegistryManager implements ICalioDynamicRegistryManager {
  private static final Gson GSON = new GsonBuilder().create();
  private static final int FILE_SUFFIX_LENGTH = ".json".length();
-
- private static final Map<RegistryAccess, CalioDynamicRegistryManager> INSTANCES = new ConcurrentHashMap<>();
  private static CalioDynamicRegistryManager clientInstance = null;
  private static CalioDynamicRegistryManager serverInstance = null;
  private boolean lock;
@@ -184,33 +178,27 @@ public static boolean isServerContext(RegistryAccess access) {
  }
 
  public static CalioDynamicRegistryManager getInstance(RegistryAccess server) {
- if (isServerContext(server))
-  return addInstance(server);
+ return isServerContext(server) ? getServerInstance() : getClientInstance();
+ }
 
+ public static CalioDynamicRegistryManager getClientInstance() {
  if (clientInstance == null)
- initializeClient();
+ clientInstance = new CalioDynamicRegistryManager();
  return clientInstance;
  }
 
- private static CalioDynamicRegistryManager addInstance(RegistryAccess server) {
+ public static CalioDynamicRegistryManager getServerInstance() {
  if (serverInstance == null)
  serverInstance = new CalioDynamicRegistryManager();
- return serverInstance;//INSTANCES.computeIfAbsent(server, s -> new CalioDynamicRegistryManager());
+ return serverInstance;
  }
 
- public static void removeInstance(RegistryAccess server) {
- //INSTANCES.remove(server);
+ public static void removeServerInstance() {
  serverInstance = null;
  }
 
- @OnlyIn(Dist.CLIENT)
- public static void initializeClient() {
- clientInstance = new CalioDynamicRegistryManager();
- }
-
- @OnlyIn(Dist.CLIENT)
- public static void setClientInstance(CalioDynamicRegistryManager clientInstance) {
- CalioDynamicRegistryManager.clientInstance = clientInstance;
+ public static void removeClientInstance() {
+ clientInstance = null;
  }
 
  public static CalioDynamicRegistryManager decode(FriendlyByteBuf buffer) {