@Heptagon, It appears you also opened a github issue for this “Non-hexadecimal number found” error flashing Klipper to EBB36 · Issue #168 · Arksine/katapult · GitHub .
It appears that Arksine made some changes back in March that keeps configs like yours from causing a problem.
I’d suggest updating the version of katapult that you are using (e.g. cd ~/katapult; git pull)