Attempt fix for Engineer's Decor and related crashes

Author: embeddedt

forge/src/main/java/org/embeddedt/modernfix/forge/config/ConfigFixer.java

@@ -0,0 +1,53 @@
+package org.embeddedt.modernfix.forge.config;
+
+import net.minecraftforge.fml.ModContainer;
+import net.minecraftforge.fml.ModList;
+import net.minecraftforge.fml.common.ObfuscationReflectionHelper;
+import net.minecraftforge.fml.config.ModConfig;
+import org.embeddedt.modernfix.ModernFix;
+
+import java.util.Optional;
+import java.util.function.Consumer;
+
+public class ConfigFixer {
+    /**
+     * To prevent mods from crashing if their ModConfigEvent is invoked by Night Config's watch thread and Forge
+     * at the same time, wrap their config handler so that it only executes the event in serial for that mod.
+     *
+     * Should have no noticeable performance impact as config handlers are virtually instant.
+     */
+    public static void replaceConfigHandlers() {
+        ModList.get().forEachModContainer((id, container) -> {
+            try {
+                Optional<Consumer<ModConfig.ModConfigEvent>> configOpt = ObfuscationReflectionHelper.getPrivateValue(ModContainer.class, container, "configHandler");
+                if(configOpt.isPresent()) {
+                    ObfuscationReflectionHelper.setPrivateValue(ModContainer.class, container, Optional.of(new LockingConfigHandler(id, configOpt.get())), "configHandler");
+                }
+            } catch(RuntimeException e) {
+                ModernFix.LOGGER.error("Error replacing config handler", e);
+            }
+        });
+    }
+
+    private static class LockingConfigHandler implements Consumer<ModConfig.ModConfigEvent> {
+        private final Consumer<ModConfig.ModConfigEvent> actualHandler;
+        private final String modId;
+
+        LockingConfigHandler(String id, Consumer<ModConfig.ModConfigEvent> actualHandler) {
+            this.modId = id;
+            this.actualHandler = actualHandler;
+        }
+
+        @Override
+        public void accept(ModConfig.ModConfigEvent modConfigEvent) {
+            synchronized (this) {
+                this.actualHandler.accept(modConfigEvent);
+            }
+        }
+
+        @Override
+        public String toString() {
+            return "LockingConfigHandler{id=" + modId + "}";
+        }
+    }
+}

forge/src/main/java/org/embeddedt/modernfix/forge/init/ModernFixForge.java

@@ -25,6 +25,7 @@
 import org.embeddedt.modernfix.forge.classloading.ModFileScanDataDeduplicator;
 import org.embeddedt.modernfix.forge.ModernFixConfig;
 import org.embeddedt.modernfix.entity.EntityDataIDSyncHandler;
+import org.embeddedt.modernfix.forge.config.ConfigFixer;
 import org.embeddedt.modernfix.forge.packet.PacketHandler;
 import org.embeddedt.modernfix.forge.registry.ObjectHolderClearer;
 import org.embeddedt.modernfix.forge.util.KubeUtil;
@@ -48,6 +49,7 @@ public ModernFixForge() {
         PacketHandler.register();
         ModFileScanDataDeduplicator.deduplicate();
         ClassLoadHack.loadModClasses();
+        ConfigFixer.replaceConfigHandlers();
     }
 
     @SubscribeEvent