Repository: withastro/astro
File: packages/astro/src/core/errors/errors-data.ts (TypeScript)

Code before:
		);
	},
} satisfies ErrorData;

/**
 * @docs
 * @see
 * - [devalue library](https://github.com/rich-harris/devalue)
 * @description
 * `transform()` functions in your content config must return valid JSON, or data types compatible with the devalue library (including Dates, Maps, and Sets).
 */
export const UnsupportedConfigTransformError = {
	name: 'UnsupportedConfigTransformError',
	title: 'Unsupported transform in content config.',
	message: (parseError: string) =>
		`\`transform()\` functions in your content config must return valid JSON, or data types compatible with the devalue library (including Dates, Maps, and Sets).\nFull error: ${parseError}`,
	hint: 'See the devalue library for all supported types: https://github.com/rich-harris/devalue',
} satisfies ErrorData;

/**
 * @docs
 * @description
 * Cannot use the module `astro:config` without enabling the experimental feature.
 */
export const CantUseAstroConfigModule = {
	name: 'CantUseAstroConfigModule',
	title: 'Cannot use the `astro:config` module without enabling the experimental feature.',
	message: (moduleName) =>
		`Cannot import the module "${moduleName}" because the experimental feature is disabled. Enable \`experimental.serializeManifest\` in your \`astro.config.mjs\` `,
} satisfies ErrorData;


/**
 * @docs
 * @kind heading
 * @name Action Errors
 */
// Action Errors
/**
 * @docs
 * @see
 * - [On-demand rendering](https://docs.astro.build/en/guides/on-demand-rendering/)
 * @description
 * Your project must have a server output to create backend functions with Actions.
 */
export const ActionsWithoutServerOutputError = {
	name: 'ActionsWithoutServerOutputError',
	title: 'Actions must be used with server output.',
	message:
		'A server is required to create callable backend functions. To deploy routes to a server, add an adapter to your Astro config and configure your route for on-demand rendering',
	hint: 'Add an adapter and enable on-demand rendering: https://docs.astro.build/en/guides/on-demand-rendering/',

Review comment (suggestion):
```suggestion
export const CantUseAstroConfigModuleError = {
	name: 'CantUseAstroConfigModuleError',
```
To match all the other errors

Code after:
 * @description
 * Content collection entries must have unique slugs. Duplicates are often caused by the `slug` frontmatter property.
 */
export const DuplicateContentEntrySlugError = {
	name: 'DuplicateContentEntrySlugError',
	title: 'Duplicate content entry slug.',
	message(collection: string, slug: string, preExisting: string, alsoFound: string) {
		return (
			`**${collection}** contains multiple entries with the same slug: \`${slug}\`. ` +
			`Slugs must be unique.\n\n` +
			`Entries: \n` +
			`- ${preExisting}\n` +
			`- ${alsoFound}`
		);
	},
} satisfies ErrorData;

/**
 * @docs
 * @see
 * - [devalue library](https://github.com/rich-harris/devalue)
 * @description
 * `transform()` functions in your content config must return valid JSON, or data types compatible with the devalue library (including Dates, Maps, and Sets).
 */
export const UnsupportedConfigTransformError = {
	name: 'UnsupportedConfigTransformError',
	title: 'Unsupported transform in content config.',
	message: (parseError: string) =>
		`\`transform()\` functions in your content config must return valid JSON, or data types compatible with the devalue library (including Dates, Maps, and Sets).\nFull error: ${parseError}`,
	hint: 'See the devalue library for all supported types: https://github.com/rich-harris/devalue',
} satisfies ErrorData;


/**
 * @docs
 * @kind heading
 * @name Action Errors
 */
// Action Errors
/**
 * @docs
 * @see
 * - [On-demand rendering](https://docs.astro.build/en/guides/on-demand-rendering/)
 * @description
 * Your project must have a server output to create backend functions with Actions.
 */
export const ActionsWithoutServerOutputError = {
	name: 'ActionsWithoutServerOutputError',
	title: 'Actions must be used with server output.',
	message:
		'A server is required to create callable backend functions. To deploy routes to a server, add an adapter to your Astro config and configure your route for on-demand rendering',