Function normalizeDateUnit

src/utils/dateModifiers.ts:55–64

(raw: string)

 * self-correcting error on anything unrecognised.
 */
export function normalizeDateUnit(raw: string): StartOf {
	const key = raw.trim().toLowerCase();
	const unit = UNIT_ALIASES[key];
	if (!unit) {
		throw new Error(
			`Unknown date unit "${raw.trim()}". Valid units: ${VALID_DATE_SNAP_UNITS}.`,
		);
	}
	return unit;
}

/**
 * Parses a single pipe segment (already stripped of its leading `|`), e.g.