return null rather than process.stdin on child process

[pfgithub]

What does this PR do?

Fixes BUN-10870, Fixes shadcn-ui/ui#6145, Fixes shadcn-ui/ui#4778, Fixes shadcn-ui/ui#5421

• bunx --bun shadcn@latest init runs npx create-next-app with node symlinked to bun
  • npx has #!/usr/bin/env node, this would resolve to bun so npx would run with bun
  • npx immediately exits with code 1, but create-next-app spawns and completes successfully
  • npx runs if (child.stdin) { child.stdin.end() }
    • the child process was spawned with inherit, so it has no stdin
    • bun was returning process.stdin in that case, rather than null like node
    • BUN-10874 process.stdin.end is Infinity rather than a function
  • TypeError: Infinity is not a function
  • npx catches this error and exits immediately with code 1
• shadcn init fails

[robobun]

^{Updated 7:08 PM PT - Feb 26th, 2025}

❌ @pfgithub, your commit 1805e4c has 3 failures in Build #12363:

• test/js/bun/http/serve-body-leak.test.ts - 5 failing on 🐧 3.20 x64-baseline
• test/cli/install/bun-install-registry.test.ts - 1 failing on 🪟 2019 x64
• test/cli/install/bun-install-registry.test.ts - 1 failing on 🪟 2019 x64-baseline
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🪟 2019 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🪟 2019 x64-baseline
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 12 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 22.04 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🍎 14 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 24.04 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 20.04 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 3.20 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🍎 13 aarch64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 22.04 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 24.04 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 22.04 x64-baseline
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 12 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 20.04 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 12 x64-baseline
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 24.04 x64-baseline
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🍎 14 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🍎 13 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 20.04 x64-baseline
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 3.20 x64
• test/js/third_party/pnpm/pnpm.test.ts - 1 failing on 🐧 3.20 x64-baseline

---

🧪   try this PR locally:

bunx bun-pr 17741