From 4c90c40761a2f7f5f78f2e098e505db68afc0b67 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marcel=20Fabian=20Kr=C3=BCger?= <tex@2krueger.de>
Date: Sun, 16 Jun 2024 10:02:03 +0200
Subject: [PATCH] Use iftex for error when not running LuaTeX to resolve #22

---
 lua-ul.dtx | 10 +++-------
 1 file changed, 3 insertions(+), 7 deletions(-)

diff --git a/lua-ul.dtx b/lua-ul.dtx
index d389573..0667c4c 100644
--- a/lua-ul.dtx
+++ b/lua-ul.dtx
@@ -942,10 +942,6 @@ require'lua-ul-patches-preserve-attr'
 % \fi
 % First define some messages.
 %    \begin{macrocode}
-\msg_new:nnnn {lua-ul} {luatex-required} {LuaLaTeX~required} {
-  Lua-UL~requires~LuaLaTeX.~
-  Maybe~you~forgot~to~switch~the~engine~in~your~editor?
-}
 \msg_new:nnnn {lua-ul} {luacolor-required} {
   Color~support~in~lua-ul~requires~luacolor.
 }{
@@ -956,9 +952,9 @@ require'lua-ul-patches-preserve-attr'
 % Only \LuaLaTeX{} is supported.
 % For other engines we show an error.
 %    \begin{macrocode}
-\sys_if_engine_luatex:F {
-  \msg_error:nn {lua-ul} {luatex-required}
-}
+\RequirePackage{iftex}
+\RequireLuaTeX
+%
 \lua_load_module:n {lua-ul}
 %
 %    \end{macrocode}