How do I select *Markdown* emphasis?

[stevenxxiu]

I'd like to be able to select the inside and outside of Markdown emphasis, e.g. for

*foo*
**bar**

I'd like to be able to easily select:

*|foo|*
|*foo*|
**|bar|**
|**bar**|

I'm not quite sure what to add, but I tried adding to ~/.config/nvim/after/queries/markdown/textobjects.scm and ~/.config/nvim/after/queries/markdown_inline/textobjects.scm:

; extends
(emphasis) @text.emphasis

The former triggers an error.

I'd like to set in ~/.config/nvim/lua/plugins/treesitter-textobjects.lua:

-- Markdown
['ae'] = '@text.emphasis',