new_contents: 
  
  class ErrorManager(object):
      """Manage all detect errors"""
      def __init__(self,):
          super().__init__()
  
          # errors is a map like this
          # {'file_name.purs': [(region1, error1), (region2, error2), ...]}
          self.errors = {}
  
      # regions_and_errors :: Array (Tuple Region Error)
      # I want type :(
      def set_errors(self, file_name, regions_and_errors):
          self.errors[file_name] = regions_and_errors
  
      def get_error_at_point(self, file_name, point):
          things = self.errors.get(file_name, [])
          for region, error in things:
              if region.contains(point):
                  return error
          return None
  
  error_manager = ErrorManager()
  
subject: Add class to manage error in files after rebuild