code: func (s *Scanner) readObjectTypeAndLength() (plumbing.ObjectType, int64, error) {
  	t, c, err := s.readType()
  	if err != nil {
  		return t, 0, err
  	}
  
  	l, err := s.readLength(c)
  
  	return t, l, err
  }
docs: // ReadObjectTypeAndLength reads and returns the object type and the
  // length field from an object entry in a packfile.