def object!(path)
      object = find_object path
      raise FileNotFoundError.new(path) if object.nil?
      object
    end
def object!(path)
      object = find_object path
      raise FileNotFoundError.new(path) if object.nil?
      object
    end
Returns the object (tree or blob) at the given path inside the repository
 or fail if it does not exist

 @param (see #find_object)
 @raise [FileNotFoundError] if no object with the given path exists
 @return (see #find_object)