yarn install fails with "ERROR: There are no scenarios; must have at least one"

I have the following line in my init.vim:

Plug 'iamcco/markdown-preview.nvim', { 'do': 'cd app && yarn install' }

But when I try to install using vim-plug, I get the this error:

**x Post-update hook for markdown-preview.nvim ... Exit status: 1**

So I tried to do it manually:
`cd ~/.local/share/nvim/plugged/markdown-preview.nvim/app`
`yarn install`

But I get this error:

**00h00m00s 0/0: : ERROR: There are no scenarios; must have at least one.**

Am I missing something?

I am running Ubuntu Linux 22.04.1 on WSL 2
I am running zsh in an Xterm

I have nodejs and yarn installed here:
/usr/bin/nodejs
/usr/bin/yarn

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