fix errors with spigot specifically.

use paper folks.

CommandWhitelistBukkit/src/main/java/eu/endermite/commandwhitelist/bukkit/CommandWhitelistBukkit.java

@@ -69,8 +69,13 @@ public class CommandWhitelistBukkit extends JavaPlugin {
 
     private void reloadPluginConfig() {
         File configFile = new File("plugins/CommandWhitelist/config.yml");
-        if (configCache == null)
+        if (configCache == null) {
+            try {
                 configCache = new ConfigCache(configFile, true, getSLF4JLogger());
+            } catch (NoSuchMethodError e) {
+                configCache = new ConfigCache(configFile, true, null);
+            }
+        }
         else
             configCache.reloadConfig();
     }
@@ -78,9 +83,11 @@ public class CommandWhitelistBukkit extends JavaPlugin {
     public void reloadPluginConfig(CommandSender sender) {
         getServer().getScheduler().runTaskAsynchronously(this, () -> {
             reloadPluginConfig();
+            try {
                 for (Player p : Bukkit.getOnlinePlayers()) {
                     p.updateCommands();
                 }
+            } catch (Exception ignored) {}
             audiences.sender(sender).sendMessage(CWCommand.miniMessage.parse(configCache.prefix + configCache.config_reloaded));
         });
     }

CommandWhitelistCommon/src/main/java/eu/endermite/commandwhitelist/common/ConfigCache.java

@@ -132,8 +132,10 @@ public class ConfigCache {
             if (commands.contains(cmd)) continue;
             commands.add(cmd);
         }
-
+        List<String> subCommands = new ArrayList<>();
-        List<String> subCommands = section.getStringList(id + ".subcommands");
+        for (String subCmd : section.getStringList(id + ".subcommands")) {
+            subCommands.add(String.valueOf(subCmd));
+        }
         String customCommandDeniedMessage = section.getString(id + ".custom_command_denied_message");
         return new CWGroup(id, commands, subCommands, customCommandDeniedMessage);
     }
@@ -148,6 +150,10 @@ public class ConfigCache {
     }
 
     private void warn(String log) {
+        if (logger == null) {
+            System.out.println("WARNING: "+log);
+            return;
+        }
         if (logger instanceof org.slf4j.Logger) {
             ((org.slf4j.Logger) logger).warn(log);
             return;