catching grpc error on setup, displaying error dialog and exiting app

coretk/coretk/app.py

@@ -98,6 +98,9 @@ class Application(tk.Frame):
     def save_config(self):
         appconfig.save(self.guiconfig)
 
+    def close(self):
+        self.master.destroy()
+
 
 if __name__ == "__main__":
     log_format = "%(asctime)s - %(levelname)s - %(module)s:%(funcName)s - %(message)s"

coretk/coretk/coreclient.py

@@ -6,6 +6,9 @@ import logging
 import os
 import time
 from pathlib import Path
+from tkinter import messagebox
+
+import grpc
 
 from core.api.grpc import client, core_pb2
 from coretk import appconfig
@@ -386,6 +389,7 @@ class CoreClient:
 
         :return: existing sessions
         """
+        try:
             self.client.connect()
 
             # get service information
@@ -408,6 +412,12 @@ class CoreClient:
             self.default_services = {
                 x.node_type: set(x.services) for x in response.defaults
             }
+        except grpc.RpcError as e:
+            if e.code() == grpc.StatusCode.UNAVAILABLE:
+                messagebox.showerror("Server Error", e.details())
+            else:
+                messagebox.showerror("GRPC Error", e.details())
+            self.app.close()
 
     def get_session_state(self):
         response = self.client.get_session(self.session_id)