pygui added error dialog for duplicate observer names and cleared out values on success

daemon/core/gui/dialogs/observers.py

@@ -1,5 +1,5 @@
 import tkinter as tk
-from tkinter import ttk
+from tkinter import messagebox, ttk
 from typing import TYPE_CHECKING
 
 from core.gui.coreclient import Observer
@@ -104,7 +104,11 @@ class ObserverDialog(Dialog):
             observer = Observer(name, cmd)
             self.app.core.custom_observers[name] = observer
             self.observers.insert(tk.END, name)
+            self.name.set("")
+            self.cmd.set("")
             self.app.menubar.draw_custom_observers()
+        else:
+            messagebox.showerror("Observer Error", f"{name} already exists")
 
     def click_save(self):
         name = self.name.get()