getError(path, value) {
    if (isObject(this.error)) {
      return this.getFailingRules(value)
        .map(key => getErrorFromObject(this.error, path, value, key));
    }
    return [getErrorFromFunctionOrString(this.error, path, value)];
  }
returns a list of errors if they are present
@return {[String]}