can1357/oh-my-pi · error · TraversalError

TraversalError thrown by OmpErrors.throw() with message equa

Error message

TraversalError thrown by OmpErrors.throw() with message equal to errors summary

What it means

`Type.assert` validation failures are aggregated into an `OmpErrors` object; calling `.throw()` wraps it in a `TraversalError`. The error's message equals the human-readable summary of all traversal errors found during validation. Catching it gives you the full `errors` object for structured inspection of every failed check.

Source

Thrown at packages/omptype/src/errors.ts:424

				entry =>
					Object.is(entry.data, entries[0].data) &&
					entry.path.length === entries[0].path.length &&
					entry.path.every((key, index) => key === entries[0].path[index]),
			)
		) {
			const at = formatPath(entries[0].path);
			const actual = typeof entries[0].data === "string" ? JSON.stringify(entries[0].data) : String(entries[0].data);
			return `${at}${at === "" ? "" : " "}(${actual}) must be...\n${entries.map(entry => `  ◦ ${entry.expected}`).join("\n")}`;
		}
		return entries.map(error => error.message).join(this.#separator);
	}

	toString(): string {
		return this.summary;
	}

	throw(): never {
		throw new TraversalError(this);
	}
}

/** Error thrown by `Type.assert` on invalid input. */
export class TraversalError extends Error {
	constructor(readonly errors: OmpErrors) {
		super(errors.summary);
		this.name = "TraversalError";
	}
}

/**
 * Definition/usage error thrown while building a schema — malformed string
 * DSL, unsupported composition, or an illegal builder call. Distinct from
 * validation failures, which are returned as {@link OmpErrors}.
 */
export class OmpTypeError extends Error {
	constructor(message: string) {

View on GitHub (pinned to 9690622007)

Solutions

1. Fix the data so it satisfies the type; read `error.summary` for the exact failing paths.
2. Catch `TraversalError` and inspect `err.errors` for per-path diagnostics.
3. Use `type.allows(value)` or a `try` around `assert` when input validity is uncertain.

Example fix

// before
type.assert(input); // throws TraversalError
// after
if (!type.allows(input)) {
  const err = type(input); // inspect per-key errors
  throw new Error(`bad input: ${err.summary}`);
}

const result = type(value); // returns errors instead of throwing
if (result instanceof type.constructor // ArkType: truthy result means valid
  ) {} else { console.log(result.summary); }

function isValid(v: unknown): boolean { return type.allows(v); }

try {
  type.assert(value);
} catch (err) {
  if (err instanceof TraversalError) {
    console.error(err.errors.summary); // per-path diagnostics
  } else throw err;
}

When it happens

Trigger: Calling `type.assert(value)` (or `.throw()` on an `OmpErrors` instance) when the validated value fails one or more type constraints.

Common situations: Validating untrusted JSON input (API payloads, config files) against an ArkType-compatible schema; type changes after schema updates; partially migrated data shapes.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• Invalid pattern: {err}
• Destination option ${key} must be a string
• Destination option ${key} must be a finite number
• Destination option ${key} must be a boolean
• wait(...) expects milliseconds (number) or a predicate funct

AI-assisted analysis of can1357/oh-my-pi@9690622007 (2026-08-31). Data as JSON: /api/errors/779a49704dfa3171. Report an issue: GitHub.