doc: update dropperCrashFix

Author: OptiJava

README-en.md

@@ -241,7 +241,27 @@ CommandLogger.json is the config file, type: `/commandlogger reload` to reload t
 
 Fix bug: dropper may cause server crash
 
-Please watch [kygo_life's bilibili video](https://www.bilibili.com/video/BV1HM411z7jz/?spm_id_from=333.999.0.0)
+The discoverer of this bug is player `kygo_life`, who [once posted an explanation on bilibili](https://www.bilibili.com/video/BV1HM411z7jz/?spm_id_from=333.999.0.0). However, it was deleted.
+
+The triggering process of this bug is roughly as follows: First, build a structure similar to an item shadowing, but replace the box with a shulker box (which can be empty). At this time, open the trapdoor, destroy the shulker box, and the update suppression will be triggered.
+
+Then place a dropper at the position of the shulker box, and then trigger it with a redstone signal (such as a lever), and boom!
+
+This bug has been tested and available in `1.17.1`, but has not been tested in other versions.
+
+General principle:
+
+- After the shadow box is broken, the update suppression is triggered, so although the shadow box blocks are broken, the shulker box block entity are still exist.
+
+- The dropper block is placed, the block is a dropper, but the block entity remains a shulker box.
+
+- When triggered, the `DropperBlock.dispense (...)` method of that dropper will be called, and that method has the following code: (This line of code is exactly the same in `yarn` 1.17.1, 1.18.2, 1.19.3, 1.20.1)
+```
+DispenserBlockEntity dispenserBlockEntity = (DispenserBlockEntity)blockPointerImpl.getBlockEntity();
+                                                  ^^^^^^^^^^
+                                                class cast here!      shulker block entity -> dispenser block entity
+``` 
+- So throwing `ClassCastException` during this can cause server crash（
 
 - Default value: `false`
 - Acceptable value: `true` `false`

README.md

@@ -248,7 +248,23 @@ CommandLogger.json配置文件可以配置白名单、黑名单等，修改配
 
 修复了方块实体替换导致投掷器激活时崩服的bug
 
-详情请看[kygo_life的视频](https://www.bilibili.com/video/BV1HM411z7jz/?spm_id_from=333.999.0.0)
+这个bug的发现人是玩家`kygo_life`，[他曾经在B站发了一个解释](https://www.bilibili.com/video/BV1HM411z7jz/?spm_id_from=333.999.0.0)，不过被删掉了。
+
+这个bug的触发流程大致如下：首先建造一个类似于物品分身的结构，只不过将箱子换成潜影盒（可为空），此时打开活板门，打掉潜影盒，此时更新抑制会被触发，然后在原本
+潜影盒的位置上放置一个投掷器，然后用红石信号（如拉杆）触发此投掷器即可崩档。
+
+本bug在`1.17.1`经测试可用，其他版本未测试。
+
+大致原理：
+- 有点像方块实体替换，潜影盒被打掉后因为触发了更新抑制，所以虽说潜影盒方块被打掉了，但是方块实体仍保留
+- 投掷器方块被放置，方块是投掷器，方块实体仍为潜影盒
+- 触发时，那个投掷器的`DropperBlock.dispense(...)`方法会被调用，而那个方法有这样一段代码：（这行代码在`yarn`1.17.1、1.18.2、1.19.3、1.20.1完全相同）
+```
+DispenserBlockEntity dispenserBlockEntity = (DispenserBlockEntity)blockPointerImpl.getBlockEntity();
+                                                ^^^^^^^^^^
+                                               进行了一次强转
+```
+- 所以在强转时抛出`ClassCastException`，崩服甚至崩档（
 
 - Default value: `false`
 - Acceptable value: `true` `false`

src/main/java/io/github/optijava/opt_carpet_addition/mixins/rule/dropperCrashFix/DropperBlock_Mixin.java

@@ -3,7 +3,7 @@
 import io.github.optijava.opt_carpet_addition.OptCarpetAddition;
 import io.github.optijava.opt_carpet_addition.OptCarpetSettings;
 import net.minecraft.block.DropperBlock;
-import net.minecraft.block.entity.DispenserBlockEntity;
+import net.minecraft.block.entity.DropperBlockEntity;
 import net.minecraft.server.world.ServerWorld;
 import net.minecraft.util.math.BlockPos;
 import org.spongepowered.asm.mixin.Mixin;
@@ -20,7 +20,7 @@ public class DropperBlock_Mixin {
             cancellable = true
     )
     public void injectDispense(ServerWorld world, BlockPos pos, CallbackInfo ci) {
-        if (OptCarpetSettings.dropperCrashFix && !(world.getBlockEntity(pos) instanceof DispenserBlockEntity)) {
+        if (OptCarpetSettings.dropperCrashFix && !(world.getBlockEntity(pos) instanceof DropperBlockEntity)) {
             OptCarpetAddition.LOGGER.fatal("[OptCarpetAddition] Detected dropper crash at %s [%s %s %s]".formatted(world.getRegistryKey().getValue().getPath(), pos.getX(), pos.getY(), pos.getZ()));
             ci.cancel();
         }