public class TemplateDoesNotExist: Error, CustomStringConvertible { let templateNames: [String] let loader: Loader? public init(templateNames: [String], loader: Loader? = nil) { self.templateNames = templateNames self.loader = loader } public var description: String { let templates = templateNames.joined(separator: ", ") if let loader = loader { return "Template named `\(templates)` does not exist in loader \(loader)" } return "Template named `\(templates)` does not exist. No loaders found" } }