withastro/astro · error · AstroError

ExpectedImageOptions

ExpectedImageOptions

Error message

**${context.collection}** entry is missing an ID.
Invalid data type: ${typeof data}

What it means

A defensive branch at the end of Astro's function-style loader handling: after the zod union (array | record) validates successfully, the data must be an array or an object; anything else falls through to this throw. In practice it is unreachable because the schema only lets arrays and objects through. Note the throw spreads `ExpectedImageOptions` while formatting the message from ContentLoaderInvalidDataError — the error code is wrong, so if you do hit this, report it as an Astro bug.

Solutions

Ensure your function-style loader returns a plain array or plain object (this error should never fire if error 80's validation passed).
If you can reproduce it, file an Astro issue — both the unreachable branch and the misattributed ExpectedImageOptions code are worth reporting.

Defensive patterns

Strategy: validation

Validate before calling

function isLoaderReturnable(v: unknown): boolean {
  return Array.isArray(v) || (v !== null && typeof v === 'object');
}

Try / catch

try {
  await getCollection('blog');
} catch (err) {
  // Note: this throw carries the ExpectedImageOptions code but a ContentLoaderInvalidDataError message
  if (/Invalid data type/.test((err as any).message)) {
    console.error('Loader returned neither array nor object');
  } else throw err;
}

Prevention

Return only plain arrays or plain objects from function-style loaders.
If this fires with normal data, report an Astro bug — the branch is unreachable by design and the error code is misattributed.

When it happens

Trigger: Not reachable through the public API: loaderReturnSchema would already have rejected non-array/non-object data with ContentLoaderReturnsInvalidId. Only exotic cases (a custom zod setup or an Astro regression) could land here.

Common situations: Essentially none; appears only for Astro-internal bugs or patched/modified zod behavior.

Related errors

AI-assisted analysis of withastro/astro@52e6c34790 (2026-08-18). Data as JSON: /api/errors/38aad68b85c71214. Report an issue: GitHub.

Appendix: source

Thrown at packages/astro/src/content/content-layer.ts:534

		return;
	}
	if (typeof data === 'object') {
		for (const [id, raw] of Object.entries(data)) {
			if (raw.id && raw.id !== id) {
				throw new AstroError({
					...AstroErrorData.ContentLoaderInvalidDataError,
					message: AstroErrorData.ContentLoaderInvalidDataError.message(
						context.collection,
						`Object key ${JSON.stringify(id)} does not match ID ${JSON.stringify(raw.id)}`,
					),
				});
			}
			const item = await context.parseData({ id, data: raw });
			context.store.set({ id, data: item });
		}
		return;
	}
	throw new AstroError({
		...AstroErrorData.ExpectedImageOptions,
		message: AstroErrorData.ContentLoaderInvalidDataError.message(
			context.collection,
			`Invalid data type: ${typeof data}`,
		),
	});
}

View on GitHub (pinned to 52e6c34790)