Thank you! You're absolutely right. The problem was that, at first, I tried to update the plugin without populating the data/LootManager/LootTables folder with files from the archive (I simply didn’t check the archive’s data folder before the update). I only added them on the second try, when I encountered a missing-file error during compilation.
After reading your comment, I checked the logs and realized that I had actually faced two different errors on the first and second attempts. So, I tried updating again.
For those who made the same mistake, here's how I fixed it:
unload both Convoy and Loot Manager → repopulate the LootTables folder → load the Loot Manager → update and load the Convoy
And finally I get:
Loaded plugin Convoy v2.8.8 by Adem [542ms]
[Convoy] The transfer of loot tables to the LootManager plugin has started!
[Convoy] A backup of the config named 'Convoy_Backup.json' has been created!
[Convoy] The transfer of loot tables has been successfully completed.
Thanks again!
Edit:
Probably, the problem was elsewhere and there's no need to populate the data/LootManager/LootTables folder manually at all. I checked the folder and found duplicates of each file. So, I tried again without copying any files: unload both Convoy and Loot Manager → load the Loot Manager → update and load the Convoy.
The process completed without errors, and there are no duplicates in the data/LootManager/LootTables folder anymore.