What causes "data is required when yield indicates success" in can1357/oh-my-pi?

Resubmit with {result: {data: }}, matching the declared schema even if the content is empty (e.g. {items: []})

data is required when yield indicates success

Error message

data is required when yield indicates success

What it means

A yield that signals success without useLastTurn must include a `data` payload. If data is null (or absent) on a non-last-turn success, the tool throws because a successful result with no content cannot be assembled or validated. Error-status yields and useLastTurn yields bypass this check.

Source

Thrown at packages/coding-agent/src/tools/yield.ts:438

				throw new Error(
					`Section ${formatYieldLabels(yieldType as string[])} uses unknown incremental yield label(s): ${formatYieldLabels(unknownLabels)}. Resubmit with one of the schema's labels: ${validLabels}.`,
				);
			}
		}
		// A schema-bound terminal last-turn yield with no accumulated sections can
		// only assemble raw prose, which finalization then rejects post-mortem as a
		// fatal schema_violation the child can no longer correct. Catch it here as
		// a retryable error instead. With sections present, a data-less finalize
		// legitimately closes the incremental flow (assembly keeps the sections).
		if (status === "success" && useLastTurn && !isIncremental && this.#validate && !this.#hasIncrementalSections) {
			throw new Error(
				"This task requires structured output matching the declared schema; a last-turn result cannot satisfy it. " +
					`Submit the full object: {"result":{"data":<object matching the schema>}}.`,
			);
		}
		if (status === "success" && !useLastTurn) {
			if (data === null) {
				throw new Error("data is required when yield indicates success");
			}
			const validateData = (value: unknown): JsonSchemaValidationResult | undefined =>
				isIncremental
					? this.#validateIncrementalSection(yieldType as string[], value)
					: this.#validate
						? this.#validate(value)
						: undefined;
			let sectionFailure = validateData(data);
			if (sectionFailure && !sectionFailure.success && typeof data === "string") {
				// Lossless recovery: a JSON-encoded payload string parses to exactly
				// the intended value (executor finalization already parses terminal
				// yields the same way). Never the reverse — stringifying objects to
				// fit string-typed fields is silent corruption.
				const parsed = parseJsonContainerString(data);
				if (parsed !== undefined) {
					const revalidated = validateData(parsed);
					if (revalidated === undefined || revalidated.success) {
						data = parsed;

View on GitHub (pinned to 9690622007)

Solutions

Resubmit with {result: {data: <your output>}}, matching the declared schema even if the content is empty (e.g. {items: []})
If there is genuinely no result and the task failed, use {result: {error: "reason"}} instead
If the answer lives in the final assistant message, use the useLastTurn variant rather than null data
Fix the caller so falsy-but-valid values are not coerced to null

Example fix

// before
yield({ result: { data: null } });
// after
yield({ result: { data: { items: [], summary: "no findings" } } });

Defensive patterns

Strategy: validation

Validate before calling

if (status === 'success' && !useLastTurn && (data === null || data === undefined)) {
  throw new TypeError('success yield requires a data payload');
}

Type guard

function successHasData(r) {
  return !(r.status === 'success' && r.useLastTurn !== true && (r.data === null || r.data === undefined));
}

Try / catch

try {
  yield({ result: { data } });
} catch (err) {
  if (err.message === 'data is required when yield indicates success') {
    yield({ result: { data: emptyButValidObject() } });
  } else throw err;
}

Prevention

Never coerce results to null — preserve falsy-but-valid values (0, "", false)
For 'nothing found', yield a schema-valid empty object (e.g. {items: []})
Route genuine failures through {result:{error}} instead of null data

When it happens

Trigger: Calling yield with a success status, useLastTurn not set, and data explicitly null or omitted — e.g. {result: {data: null}} or {result: {status: "success"}}.

Common situations: A caller converts a falsy result (empty string, 0, false) into null before yielding; a template leaves the data field blank; an agent finishes with 'nothing to report' instead of yielding an empty-but-schema-valid object.

Understand the failure class

Background: "Missing required field" and "field is required" errors: why libraries reject payloads that omit mandatory fields — this error's family across 20 libraries.

Related errors

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/045991b66a1ee86a. Report an issue: GitHub.