This was a bug in the latest v4l-utils/ir-keytable version, I found and fixed it
v4l-utils: add patch to fix crash in ir-keytable by HiassofT · Pull Request #8438 · LibreELEC/LibreELEC.tv
Recent keytable changes missed to properly initialize a buffer pointer so it used random memory when reading keymaps in legacy format and crashed:
LibreELEC:~…
github.com
The next LE12 nightly should work fine again with keymaps in the old (non-toml) format
so long,
Hias