Write one yourself xd.
I haven't seen any good public ingame lua editors.
You can use a frame with some html lua highlighter and a button that gets lua code from html and does CompileString or something.
Garry's Mod
LUA Editor Request!
Submitted by kanakun, 10-01-2018, 04:25 PM, Thread ID: 69247
Thread Closed
RE: LUA Editor Request! 21-01-2018, 08:24 PM #8
21-01-2018, 08:24 PM
#8