/// A protocol that native error types can conform to in order to control
/// how they are represented when thrown into the JavaScript world.
///
/// When a native function throws an error that conforms to this protocol,
/// a JavaScript `Error` object is created with the specified `message`
/// and `code`.
///
/// Types that don't conform to this protocol are still throwable, but
/// will use a generic error representation.
///
/// ```swift
/// struct MyError: JavaScriptThrowable {
///   var message: String { "Something went wrong" }
///   var code: String { "ERR_MY_ERROR" }
/// }
/// ```
public protocol JavaScriptThrowable: Error, Sendable {
  /// The error message describing what went wrong. Defaults to the debug description of the
  /// conforming type, which typically includes richer context (class name, origin, cause chain)
  /// than a plain description. Override to provide a custom user-facing message.
  var message: String { get }

  /// An error code for programmatic error handling in JavaScript.
  /// Return an empty string to omit the `code` property from the JS error.
  var code: String { get }
}

extension JavaScriptThrowable {
  public var message: String {
    return String(reflecting: self)
  }

  public var code: String {
    return ""
  }
}