Delete EmptyRestAction

This has the problem of not fully conforming to the contract of
RestAction and therefore risking unspecified behavior. The one use of
this is rewritten to use normal RestAction semantics.

Author: sciwhiz12

src/core/java/com/mcmoddev/mmdbot/core/commands/CommandUpserter.java

@@ -23,7 +23,6 @@
 import com.jagrosh.jdautilities.command.CommandClient;
 import com.jagrosh.jdautilities.command.ContextMenu;
 import com.jagrosh.jdautilities.command.SlashCommand;
-import com.mcmoddev.mmdbot.core.util.EmptyRestAction;
 import com.mcmoddev.mmdbot.core.util.config.SnowflakeValue;
 import lombok.NonNull;
 import net.dv8tion.jda.api.JDA;
@@ -140,12 +139,14 @@ public void upsertCommands(@NonNull final JDA jda) {
                 final var guild = guildId.resolve(jda::getGuildById);
                 if (guild != null) {
                     // Guild still specified? Then remove guild commands
-                    guild.retrieveCommands()
-                        .flatMap(commands -> commands.isEmpty() ? EmptyRestAction.empty() : RestAction.allOf(commands.stream()
-                            .map(Command::getIdLong)
-                            .map(guild::deleteCommandById)
-                            .toList()))
-                        .queue();
+                    guild.retrieveCommands().queue(commands -> {
+                        if (!commands.isEmpty()) {
+                            RestAction.allOf(commands.stream()
+                                .map(Command::getIdLong)
+                                .map(guild::deleteCommandById)
+                                .toList()).queue();
+                        }
+                    });
                 }
             }
             jda.retrieveCommands().queue(commands -> {