exception decorator and mail send for errors and changes to rec state checker

backend/serve_frontend.py

@@ -16,6 +16,7 @@ if not os.path.exists(fe_path) or not os.path.exists(os.path.join(fe_path, "inde
     app.logger.critical(
         "Frontend path and/or index.html does not exist! Please build frontend before continuing! "
         "You might want to go to ../frontend and continue from there.")
+    print("FATAL: Frontend path wrong or index.html missing -> EXITING!")
     exit()
 fe_bp = Blueprint('frontend', __name__, url_prefix='/', template_folder=os.path.join(fe_path, ""))