If you are interested in small Lua-based text editors, I advise you to take a look at Textadept: https://foicica.com/textadept/ . Specifically as to minimalism: "Relentlessly optimized for speed and minimalism over the years, the editor consists of less than 2000 lines of C code and less than 4000 lines of Lua code." I believe this is a limit that the editor's author self-imposed and keeps to it with an impressive strictness.

edit: though it uses Scintilla for the "engine" and I would assume its LOC count is not counted towards this limit.