import type { ExprValue } from './types/expr-value';
/**
 * When a translation hits an error, log and return one of these as a value.
 * This will allow the rest of the translation walk to complete. The
 * generated SQL will have a reference to an impossible variable name
 * with the reason embedded in it.
 * @param reason very short phrase, only read by implementers
 * @return Expr which a debugging humnan will regognize
 */
export declare function errorFor(reason: string): ExprValue;