import argparse

parser = argparse.ArgumentParser(exit_on_error=False)
subparsers = parser.add_subparsers(required=True)
sub = subparsers.add_parser("sub", exit_on_error=False)
sub.add_argument("arg", type=int)

parser2 = argparse.ArgumentParser(exit_on_error=False)
parser2.add_argument("arg", type=int)

try:
    #parser.parse_args([]) # Doesn't work, the process just exits instead of ArgumentError getting caught
    #parser.parse_args(["invalid"]) # Invalid arguments work, ArgumentError gets caught
    #parser.parse_args(["sub"]) # Doesn't work, the process just exits instead of ArgumentError getting caught
    #parser2.parse_args([]) # Doesn't work, the process just exits instead of ArgumentError getting caught
    parser2.parse_args("a") # Invalid arguments work, ArgumentError gets caught
    print("okay")
except argparse.ArgumentError as ae:
    print("ArgumentError", ae)