On lines 1025-1026 the plugin looks for the player.blueprints.#.db file. If the server is using the Harmony Mod to prevent blueprint wipes, this isn't picked up and throws errors on the server. The HarmonyMod renames the file to be "player.blueprints.db" and any player.blueprints.#.db on the server will be read on error until deleted.

#if RUST
        _saveInfo ??= SaveInfo.Create(World.SaveFolderName +
                                      $"/player.blueprints.{Rust.Protocol.persistance}.db");

I'm not a programmer but I think just using below will fix the issue. NOT TESTED.

#if RUST
        _saveInfo ??= SaveInfo.Create(World.SaveFolderName +
                                      $"/player.blueprint*.db");