fix(application-form): handle no options provided

Users with the right permissions could create a menu with no roles, and
that would cause an error.

Refs: #1024

application/src/main/java/org/togetherjava/tjbot/features/basic/ApplicationCreateCommand.java

@@ -119,7 +119,13 @@ public void onSlashCommand(SlashCommandInteractionEvent event) {
  return;
  }
 
- long incorrectArgsCount = getIncorrectRoleArgsCount(event.getInteraction().getOptions());
+ final List<OptionMapping> optionMappings = event.getInteraction().getOptions();
+ if (optionMappings.isEmpty()) {
+ event.reply("You have to select at least one role.").setEphemeral(true).queue();
+ return;
+ }
+
+ long incorrectArgsCount = getIncorrectRoleArgsCount(optionMappings);
  if (incorrectArgsCount > 0) {
  event.reply("Missing information for %d roles.".formatted(incorrectArgsCount))
  .setEphemeral(true)