Cannot parse config, bad conversion

Hi. I'm trying to make Tab send Hyper_L and Backslash send Hyper_R when held, while sending their normal keys when tapped. However, whenever I start my systemd service, the interception doesn't work. The output of systemctl status udevmon.service contains this error:

Nov 11 12:10:26 eva-desktop nice[15172]: dual-function-keys: cannot parse '/home/daniel/repos/keyboard-settings/tab-backslash-hypers.yaml': yaml-cpp: error at line 7, column 11: bad conversion

Here is the full systemctl status udevmon.service output, alongside with all the configs and keyboard info: https://gist.github.com/NightH4nter/20f7ab3234fc047e08ebb9a9355517ea.

This behavior is the same on bspwm (+sxhkd) and Openbox.