message: change Exception class
diff: @@ -36,7 +36,7 @@ namespace arangodb {
  namespace velocypack {
  // base exception class
  -struct Exception : std::exception {
  +class Exception : public virtual std::exception {
  public:
  enum ExceptionType {
  InternalError = 1,
  @@ -75,15 +75,17 @@ struct Exception : std::exception {
  };
  private:
  - ExceptionType _type;
  + ExceptionType const _type;
  char const* _msg;
  public:
  - Exception(ExceptionType type, char const* msg) noexcept : _type(type), _msg(msg) {}
  + Exception(ExceptionType type, char const* msg) : _type(type), _msg(msg) {}
  - explicit Exception(ExceptionType type) noexcept : Exception(type, message(type)) {}
  + explicit Exception(ExceptionType type) : Exception(type, message(type)) {}
  - Exception(Exception const& other) noexcept : _type(other._type), _msg(other._msg) {}
  + Exception(Exception const& other) : _type(other._type), _msg(other._msg) {}
  +
  + ~Exception() = default;
  char const* what() const noexcept { return _msg; }
  