Find a way to abstract slash command validation

[Bwen]

As an example here is the validation function for the admin:groups:del

async function validateAndParse(values) {
  if (values === undefined || !values.length) {
    throw new MissingArgumentError(MODULE_PATH);
  }

  const promises = values.map((name) => db.Group.findOne({ where: { name } }));
  const groups = await Promise.all(promises);

  // Check for invalid groups
  groups.forEach((group, index) => {
    if (group === null) {
      throw new InvalidArgumentError(MODULE_PATH, `Group not found \`${values[index]}\``);
    }
  });

  return groups;
}

This logic is duplicated/repeated all over the admin slash commands. It would be nice to find a way to abstract it in a way that is generic enough to re-use for most slash commands.