`rails new website --js=esbuild` silently fails when yarn isn't installed

[j127]

rails new silently fails when yarn isn't installed, resulting in a broken project.

Steps to reproduce

Create a new Rails project like this:

rails _8.0.2_ new my_website --js=esbuild --css=tailwind --database=postgresql

Expected behavior

The command should fail because the resulting project is broken.

Actual behavior

The project gets generated, but it's broken due to no npm dependencies.

Here's the resulting package.json which is missing tailwind, esbuild, and hotwire dependencies:

{
  "name": "app",
  "private": true,
  "scripts": {
    "build": "esbuild app/javascript/*.* --bundle --sourcemap --format=esm --outdir=app/assets/builds --public-path=/assets",
    "build:css": "npx @tailwindcss/cli -i ./app/assets/stylesheets/application.tailwind.css -o ./app/assets/builds/application.css --minify"
  }
}

System configuration

Rails version: 8.0.2

Ruby version: ruby 3.4.2 (2025-02-15 revision d2930f8e7a) +PRISM [arm64-darwin24]

(M1 MacBook)