Right I have seen this happen before. I am actually surprised that systemd
doesn't manage this automatically ...
Do you have a Linux machine at hand ? This would also include a BeagleBone Black that is part of a Bela system. If you do, then follow the instructions here to resize it. If you indeed have a BeagleBone Black with a valid eMMC, then you can use the instructions here to access the SD card when booting from the eMMC. Otherwise, if you have a Windows machine, there should be a way of adding a driver for R/W access to an ext4
partition (such as the one on Bela). Then you'd go there and delete the log files from /var/log/
on the SD card. On macos, as far as I am aware, the only available solutions are commercial (e.g.: from Paragon).
So if you are on mac, maybe you can just make a copy of the SD card to a file (using the instructions here) and send me that file and I can edit that for you and send it back to you.
Ultimately, if you have a copy of the project on your own computer, you may just want to flash a new SD card and put the program back there.