can1357/oh-my-pi · error · OmpTypeError

ParseError: ${heading} ${error.problem}

Error message

ParseError: ${heading} ${error.problem}

What it means

omptype wraps underlying parse failures in an OmpTypeError whose message is `ParseError: <heading> <problem>`. The heading is built from the type/property path segments where the default value was being normalized (e.g. `.myProp`), and `error.problem` describes why the default expression was rejected. `invalidDefault` is invoked by `normalizeDefaults` and `.default()` when a default fails validation against its own type.

Source

Thrown at packages/omptype/src/type.ts:623

	target.resolver = source.resolver;
	Reflect.set(target, "$", source.$);
	return target;
}
function invalidDefault(label: string, errors: OmpErrors): never {
	const error = errors[0];
	let heading = label;
	for (let index = 0; index < error.path.length; index++) {
		const segment = error.path[index];
		if (typeof segment === "number") {
			if (label === "Default" && index === 0) heading = "Default value";
			heading += ` at [${segment}]`;
		} else if (label === "Default" && index === 0) {
			heading += ` ${String(segment)}`;
		} else {
			heading += `.${String(segment)}`;
		}
	}
	throw new OmpTypeError(`ParseError: ${heading} ${error.problem}`);
}

function rejectMutableStaticDefault(value: unknown): void {
	if (value !== null && typeof value === "object" && !(value instanceof Date)) {
		throw new OmpTypeError("ParseError: A mutable default value must be specified as a factory");
	}
}

function normalizeDefaults(ir: IR, seen = new WeakSet<object>()): void {
	if (seen.has(ir)) return;
	seen.add(ir);
	switch (ir.k) {
		case "object":
			for (const prop of ir.props) {
				normalizeDefaults(prop.val, seen);
				if (!prop.hasDefault || prop.defValidated) continue;
				let candidate: unknown;
				let factory = false;

View on GitHub (pinned to 9690622007)

Solutions

1. Read `error.problem` in the message — it states the exact constraint the default violates.
2. Change the default to a value that satisfies the type (e.g. `type('number>5').default(10)`).
3. Use a factory `.default(() => value)` if a computed or Date-valued default is intended.
4. Re-check the path in the heading to find which nested property's default is wrong.

Example fix

// before
const T = type('number > 5').default(3); // ParseError

// after
const T = type('number > 5').default(10);

// validate the default against the type before calling .default
if (!T.allows(candidateDefault)) {
  throw new Error(`default ${JSON.stringify(candidateDefault)} fails type`);
}
const T2 = T.default(candidateDefault);

function isValidDefault(T, value) {
  return T.allows(value);
}

try {
  const T = type('number>5').default(3);
} catch (e) {
  if (e instanceof OmpTypeError && e.message.startsWith('ParseError:')) {
    console.error(e.message); // includes path heading + problem
  } else throw e;
}

When it happens

Trigger: Calling `.default(value)` with a value that does not satisfy the type, or defining an object property default that fails its own constraint (e.g. `type('number > 5').default(3)`), or a nested prop default that violates the prop type.

Common situations: Refactoring a type's constraints after setting defaults so the stale default no longer validates; copy-pasting defaults between fields with different types; typos like `.default('1')` on a number type.

Related errors

• ParseError: A mutable default value must be specified as a f
• Invalid RAR5 archive: ${reason}
• Unsupported language '{value}'. Supported: {}
• Unable to infer language from file extension: {}. Specify `l
• Invalid pattern: {err}

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/28d56698ce12d0b1. Report an issue: GitHub.