As @Jannis mentioned, the problem lies in the SilenceWarden class. When digging into the problem, I realized that something was wrong with the constructor. So I tried the plugin without said constructor to no avail. Then I realized that SilenceWarden extended JavaPlugin for some reason, something that only the main class may do. So I deleted that extension and presto! I don't know how that happened, maybe ChatGPT didn't know what it was doing. Thanks for your help!