fix client file configuration respectedly

src/main/java/whirlfrenzy/itemdespawntimer/config/ServerConfig.java

@@ -2,6 +2,7 @@ package whirlfrenzy.itemdespawntimer.config;
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import net.fabricmc.api.EnvType;
 import net.fabricmc.loader.api.FabricLoader;
 import net.minecraft.core.registries.BuiltInRegistries;
 import net.minecraft.world.entity.item.ItemEntity;
@@ -18,6 +19,15 @@ public final class ServerConfig {
     }
     private ServerConfig() {}
     public static void load() {
+        // The common/main initializer also runs in a physical Minecraft client.
+        // Never create or read the server config there: a client installation owns
+        // presentation settings only. Integrated singleplayer uses server defaults
+        // in memory; a dedicated server owns the persistent server config file.
+        if (FabricLoader.getInstance().getEnvironmentType() != EnvType.SERVER) {
+            data = new Data();
+            return;
+        }
+
         Path p = FabricLoader.getInstance().getConfigDir().resolve("item-despawn-timer-server.json");
         try {
             if (Files.exists(p)) { try (Reader r=Files.newBufferedReader(p)) { Data d=GSON.fromJson(r,Data.class); if(d!=null)data=d; } }