New Issue: [Bug]: Argument parser doesn't error about unknown flag names

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28460, "jabraham17", "[Bug]: Argument parser doesn't error about unknown flag names", "2026-02-26T18:42:05Z"

The following code demonstrates the issue

use ArgumentParser;

proc main(args: [] string) {
  var parser = new argumentParser();


  var fooFlag = parser.addFlag(name="foo", defaultValue=false);
  var arg = parser.addArgument(name="x", numArgs=1);

  parser.parseArgs(args);

  writeln("foo is ", fooFlag.valueAsBool());
  writeln("arg is ", arg.value());
}

If I compile and run this code, I should be required to provide a positional argument

./myApp
x Required value missing

If I provide the positional argument and an unknown flag, I get the proper error

./myApp x --bar
Found some unrecognizable arguments: --bar

But if I just pass an unknown flag, I get no error

./myApp --bar
foo is false
arg is --bar

The same behavior occurs with optional arguments specified as numArgs=0..1 or multiple arguments like numArgs=2 or numArgs=0..2