message: Change Small thing with soft-error
  prop(src): replace "logger.warn(new Error("Message"))" with "logger.warn("Message")"
diff: @@ -369,15 +369,11 @@ export function prop(options: PropOptionsWithValidate = {}) {
  // soft errors
  {
  if ('items' in options) {
  - logger.warn(new Error(
  - format('You might not want to use option "items" in a @prop, use @arrayProp (%s.%s)', utils.getName(target), key)
  - ));
  + logger.warn('You might not want to use option "items" in a @prop, use @arrayProp (%s.%s)', utils.getName(target), key);
  }
  if ('of' in options) {
  - logger.warn(new Error(
  - format('You might not want to use option "of" in a @prop, use @mapProp (%s.%s)', utils.getName(target), key)
  - ));
  + logger.warn('You might not want to use option "of" in a @prop, use @mapProp (%s.%s)', utils.getName(target), key);
  }
  }
  @@ -401,9 +397,7 @@ export function mapProp(options: MapPropOptions) {
  const Type = options.of;
  if ('items' in options) {
  - logger.warn(new Error(
  - format('You might not want to use option "items" in a @mapProp, use @arrayProp (%s.%s)', utils.getName(target), key)
  - ));
  + logger.warn('You might not want to use option "items" in a @mapProp, use @arrayProp (%s.%s)', utils.getName(target), key);
  }
  baseProp({
  @@ -425,9 +419,7 @@ export function arrayProp(options: ArrayPropOptions) {
  const Type = options.items;
  if ('of' in options) {
  - logger.warn(new Error(
  - format('You might not want to use option "of" in a @arrayProp, use @mapProp (%s.%s)', utils.getName(target), key)
  - ));
  + logger.warn('You might not want to use option "of" in a @arrayProp, use @mapProp (%s.%s)', utils.getName(target), key);
  }
  if ('items' in options) {
  