public extension PureYAML.Validation {
    /// Path-aware validation error.
    struct ValidationError: Swift.Error, Equatable, Sendable, CustomStringConvertible {
        public var severity: Severity
        public var reason: String
        public var path: Path

        public init(
            severity: Severity,
            reason: String,
            path: Path = .root,
        ) {
            self.severity = severity
            self.reason = reason
            self.path = path
        }

        /// Strips a trailing period from `reason` and renders the location consistently:
        /// `"<reason> at root of document"` at the root, `"<reason> at path: <path>"` elsewhere.
        /// `severity` is a separate stored property (see `Result.errors`/`.warnings`), not rendered here.
        public var description: String {
            let reasonText = reason.hasSuffix(".") ? String(reason.dropLast()) : reason
            return path.isRoot ? "\(reasonText) at root of document" : "\(reasonText) at path: \(path.description)"
        }
    }
}