# Read all the content on the file as a raw sequence of bytes.
	#
	# ~~~
	# var content = "/etc/issue".to_path.read_all_bytes
	# print content.to_s
	# ~~~
	#
	# `last_error` is updated to contains the error information on error, and null on success.
	# In case of error, the result might be empty or truncated.
	fun read_all_bytes: Bytes
	do
		var s = open_ro
		var res = s.read_all_bytes
		s.close
		last_error = s.last_error
		return res
	end