Fix poetenial issues in parser.py

[minggangw]

This PR tightens up the rosidl_parser/parser.py CLI wrapper used by the Node-side rosidl_parser.js helper by removing unused code and correcting the expected CLI argument count.

Changes:

• Remove an unused rosidl_parser import.
• Remove an unused intermediate msg_name variable.
• Update the CLI argument count check to require 3 parameters after the script name (command, package, file path).

Fix: #1403

[Copilot]

Pull request overview

This PR tightens up the rosidl_parser/parser.py CLI wrapper used by the Node-side rosidl_parser.js helper by removing unused code and correcting the expected CLI argument count.

Changes:

• Remove an unused rosidl_parser import.
• Remove an unused intermediate msg_name variable.
• Update the CLI argument count check to require 3 parameters after the script name (command, package, file path).

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[Copilot]

The CLI argument count check should likely reject both too-few and too-many arguments. Since this script expects exactly 3 parameters after the script name (command, packageName, filePath), consider checking len(sys.argv) != 4 and printing a usage string so callers can diagnose failures quickly. Also consider printing this error to stderr (like idl_parser.py does), otherwise Node’s execFile error handling may show an empty stderr.

Suggested change

	if len(sys.argv) < 4:
	print('Wrong number of argments')
	if len(sys.argv) != 4:
	print('Usage: {} <command> <packageName> <filePath>'.format(sys.argv[0]), file=sys.stderr)

[Copilot]

Typo in error message: "argments" should be "arguments".

Suggested change

	print('Wrong number of argments')
	print('Wrong number of arguments')

[coveralls]

coverage: 85.461% (+0.02%) from 85.441%
when pulling 45a406d on minggangw:fix-1403
into 1b3fdb9 on RobotWebTools:develop.