test wether the file exists before opening

standalone_tui.py

@@ -125,6 +125,9 @@ if __name__ == "__main__":
     parser.add_argument("-n", "--number", default=10, help="number of questions to ask", type=int, action="store")
     args = parser.parse_args()
     filepath = pathlib.Path(args.file)
+    if not filepath.exists():
+        print("no such file!")
+        exit(1)
     interface = Tui()
     app = Application(filepath, interface, args.number)
     try: