🐛 Avoid printing default: None in the help section when using Rich

[mattmess1221]

Related to #465

Improves consistency with Typer(rich_markup_mode=None) (TyperArgument.get_help_record), which does not print the default value if it is None.

[svlandeg]

Thanks for your PR @mattmess1221! I'll put this on my queue to review in detail and will get back to you 🙏

[svlandeg]

Thanks for your work on this, @mattmess1221!

It's true that in Rich mode, the help text prints [default: None] which is unhelpful, because the argument is still required and the default effectively useless.

When printing the help without Rich, these None defaults are suppressed with the code in core.py as you referenced:

typer/typer/core.py

Lines 351 to 355 in 74e0923

	show_default_is_str = isinstance(self.show_default, str)
	if show_default_is_str or (
	default_value is not None and (self.show_default or ctx.show_default)
	):

It makes sense to ensure the same behaviour whether or not we're printing with Rich, and for clarity I agree to copy the structure from core.py into rich_utils.py. This also means adding the check for ctx.show_default which seems to have been missing previously.

I'll leave this to Tiangolo for a final review.

Thanks again!

[tiangolo]

Nice, thank you! 🚀

And thanks for the review @svlandeg 🙌

This will be available in Typer 0.17.2 in the next minutes. 🤓