Failed to call hook 'RemoveExistingDome' on plugin 'ZoneDomes v2.0.0' (NullReferenceException: Object reference not set to an instance of an object)
  at Oxide.Plugins.ZoneDomes.TranslateMessage (BasePlayer player, System.String key, System.String additional) [0x00033] in :0

  at Oxide.Plugins.ZoneDomes.RemoveExistingDome (BasePlayer player, System.String zoneId) [0x00013] in :0

  at Oxide.Plugins.ZoneDomes.DirectCallHook (System.String name, System.Object& ret, System.Object[] args) [0x0064a] in :0

  at Oxide.Plugins.CSharpPlugin.InvokeMethod (Oxide.Core.Plugins.HookMethod method, System.Object[] args) [0x00079] in <87ce9ac9776a48658bc55eae6debe38b>:0

  at Oxide.Core.Plugins.CSPlugin.OnCallHook (System.String name, System.Object[] args) [0x000d8] in :0

  at Oxide.Core.Plugins.Plugin.CallHook (System.String hook, System.Object[] args) [0x00060] in :0

Hello @VirtualGamerGirl.

It seems to be an issue with the translation.
You can try to delete the oxide/lang/en/ZoneDomes.json file and restart the plugin in order to generate a new fresh translation file. Or you can check if your translation file contains both "Error.NoEntity" and "Notification.RemoveSuccess" entries.

I deleted the file and reloaded the plugin without any errors. I'll check it next restart and see if the error comes back. Thank you for the help and quick reply <3
Much Love VGG <3