Fix chat signatures desyncing when cancelling __on_player_message (#1778)

src/main/java/carpet/mixins/PlayerList_scarpetEventsMixin.java

@@ -2,6 +2,8 @@ package carpet.mixins;
 
 import carpet.fakes.ServerPlayerInterface;
 import carpet.script.external.Vanilla;
+import net.minecraft.network.chat.ChatType;
+import net.minecraft.network.chat.PlayerChatMessage;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.players.PlayerList;
@@ -13,6 +15,7 @@ import org.spongepowered.asm.mixin.injection.Inject;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfo;
 import org.spongepowered.asm.mixin.injection.callback.CallbackInfoReturnable;
 
+import static carpet.script.CarpetEventServer.Event.PLAYER_MESSAGE;
 import static carpet.script.CarpetEventServer.Event.PLAYER_RESPAWNS;
 
 @Mixin(PlayerList.class)
@@ -26,6 +29,17 @@ public class PlayerList_scarpetEventsMixin
         PLAYER_RESPAWNS.onPlayerEvent(player);
     }
 
+    @Inject(method = "broadcastChatMessage(Lnet/minecraft/network/chat/PlayerChatMessage;Lnet/minecraft/server/level/ServerPlayer;Lnet/minecraft/network/chat/ChatType$Bound;)V",
+            at = @At("HEAD"),
+            cancellable = true)
+    private void cancellableChatMessageEvent(PlayerChatMessage message, ServerPlayer player, ChatType.Bound params, CallbackInfo ci) {
+        // having this earlier breaks signatures
+        if (PLAYER_MESSAGE.isNeeded())
+        {
+            if (PLAYER_MESSAGE.onPlayerMessage(player, message.signedContent())) ci.cancel();
+        }
+    }
+
     @Inject(method = "respawn", at = @At(
             value = "INVOKE",
             target = "Lnet/minecraft/server/level/ServerPlayer;initInventoryMenu()V"