I already replied to this git comments.
And i replied again here why.
its already changed 3 weeks ago (9 march 2025) so if people using latest rathena before that commit, will have that issue.
https://github.com/rathena/rathena/blob/6ac181503f9317692521bde0073cb8e5c6b14fa6/npc/re/merchants/Extended_Ammunition.txt
See that file before that commit. that commit happens 3 weeks ago which is 9 march 2025. it changed this file.
https://github.com/rathena/rathena/commit/139ea0b5b393c3b19b07103245c16f756a2b8d2d#diff-1d06ccaac468f1155a6018c8ab3271064538967aac6cd396f43af7e642f7a9c0
They track from official its using close; but in rAthena it doesnt yet supported as Atemo said.
Official script uses "callshop" then "close" for these NPCs, but rAthena doesn't currently support this. That's why these scripts have been modified/reverted (hopefully temporarily) in 11d373a
So if you are downloading this rathena since before this PR update around 48hours ago till last 3 weeks, the debug warning will appear.
If you didnt believe it, try to download rAthena dated around 2 weeks ago, and try. Or try update that rAthena just a few days after 8 March 2025.