/**
 * Safely extracts a human-readable message from an unknown error value.
 *
 * This utility eliminates the repeated `error instanceof Error ? error.message : String(error)`
 * pattern used throughout the codebase for safe error-to-string conversion.
 *
 * @param error - The error value to extract a message from (may be an Error, string, or any other type).
 * @returns The error message string.
 */
export declare function toErrorMessage(error: unknown): string;