private async _autocompleteAddItem(interaction: Subcommand.AutocompleteInteraction) {
    const focusedOption = interaction.options.getFocused(true);
    let autocompleteChoices: ApplicationCommandOptionChoiceData<string>[];

    if (focusedOption.name === 'type') {
        autocompleteChoices = [
            {
                name: 'Please select an item category first.',
                value: 'invalid'
            }
        ];

        const itemCategoryIdentifier = interaction.options.getString('category');

        if (itemCategoryIdentifier) {
            const itemCategory = this.container.application.shops.itemCategories.find(
                (itemCategory) => itemCategory.identifier === itemCategoryIdentifier
            );

            if (!itemCategory) {
                throw new TypeError(`Unknown item category identifier ${itemCategoryIdentifier}`);
            }

            autocompleteChoices = itemCategory.types.map((type) => {
                const { name, identifier } = type;

                return {
                    name,
                    value: identifier
                };
            });
        }
    } else {
        throw new TypeError(`Unknown autocomplete option "${focusedOption.name}"`);
    }

    const query = focusedOption.value;
    await interaction.respond(new AutocompleteQuery(autocompleteChoices, query).results);
}

private async _autocompleteAddItem(interaction: Subcommand.AutocompleteInteraction) {
    const focusedOption = interaction.options.getFocused(true);
    let autocompleteChoices: ApplicationCommandOptionChoiceData<string>[];

    if (focusedOption.name === 'type') {
        autocompleteChoices = [
            {
                name: 'Please select an item category first.',
                value: 'invalid'
            }
        ];

        const itemCategoryIdentifier = interaction.options.getString('category');

        if (itemCategoryIdentifier) {
            const itemCategory = this.container.application.shops.itemCategories.find(
                (itemCategory) => itemCategory.identifier === itemCategoryIdentifier
            );

            if (!itemCategory) {
                throw new TypeError(`Unknown item category identifier ${itemCategoryIdentifier}`);
            }

            autocompleteChoices = itemCategory.types.map((type) => {
                const { name, identifier } = type;

                return {
                    name,
                    value: identifier
                };
            });
        }
    } else {
        throw new TypeError(`Unknown autocomplete option "${focusedOption.name}"`);
    }

    const query = focusedOption.value;
    await interaction.respond(new AutocompleteQuery(autocompleteChoices, query).results);
}