Minecraft 1.9.1 Pre-Release 2, Minecraft 1.9.1, Minecraft 1.9.2, Minecraft 1.10.2, Minecraft 16w41a, Minecraft 16w42a, Minecraft 1.11, Minecraft 1.11.2, Minecraft 1.12, Minecraft 1.12.1 Pre-Release 1, Minecraft 1.12.1, Minecraft 1.12.2
When using the /worldborder damage command with any argument except the allowed ones creates no command feedback.
Use the following command
→ No command feedback is displayed in the chat
The following is based on decompiled version of Minecraft 1.9 using MCP 9.24 beta. All method and class names are the names used in the decompiled version.
The reason why this happens is because the method net.minecraft.command.CommandWorldBorder.execute(MinecraftServer, ICommandSender, String) only tests if the given argument is "buffer" or "amount". It should however throw a WrongUsageException if this is not the case.