Swift field-level input validation collector

import Foundation

struct FieldError: Error, CustomStringConvertible {
    let field: String
    let message: String
    var description: String { "\(field): \(message)" }
}

func validate(name: String, email: String, age: Int) -> [FieldError] {
    var errors: [FieldError] = []
    if name.trimmingCharacters(in: .whitespaces).isEmpty {
        errors.append(FieldError(field: "name", message: "required"))
    }
    if !email.contains("@") {
        errors.append(FieldError(field: "email", message: "invalid address"))
    }
    if !(0...150).contains(age) {
        errors.append(FieldError(field: "age", message: "must be 0-150"))
    }
    return errors
}