Sorry for not responding earlier, I was busy with schoolwork 
I think you have misunderstood me - I have not reinstalled Garuda, I have managed to restore the partition table of the USB containing my installation of Garuda (not an installer Live USB, a real Garuda installation performed previously from a separate Live CD installer). Since I still want to transfer that installation to my HDD, I used clonezilla, as advised here, and without messing up my partition table this time. But after the transfer from my USB to the HDD, the system seems to boot up normally until it displays this error message. Booting up from my USB still lets the system startup normally.