Curses could not find terminal

[Gribouillis]

I think what may happen is that the lxterminal closes immediately after the program exits. You could try

import argparse
import subprocess
import sys
import traceback
 
def main_work(args):
    print('Hello from term-example')
 
def main():
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--noterminal',
        help="don't start a new terminal'",
        action='store_true')
    ns = parser.parse_args()
    try:
        sys.stdout.fileno()
    except Exception:
        # not a terminal for sure
        if ns.noterminal:
            raise RuntimeError('Need a terminal to run.')
        else:
            subprocess.call(['lxterminal', '-e', '{} {} --noterminal'.format(sys.executable, __file__)])
    else:
        try:
            main_work(ns)
        except Exception:
            if ns.noterminal:
                traceback.print_exc()
                input()# <---- this is to prevent the program to end and close the terminal
            else:
                raise
        else:
            if ns.noterminal:
                input() # <---- this is to prevent the program to end and close the terminal
     
if __name__ == '__main__':
    main()

Also you can try to run directly this command in a terminal to see if it says anything (this is not python):

lxterminal -e "python3 Calculator.py --noterminal"

Edit: I installed lxterminal in my kubuntu system and the above code works!
Edit: Support added for holding the terminal if the program fails (with exception).