Build fails when package has no scripts

Created by: renato-bohler

Describe the bug

When running react-scripts build the build fails if:

the project has no scripts on its package.json AND
the public pathname is set (via "homepage" on package.json or the PUBLIC_URL env variable) AND
the public pathname contains .github.io/

This might happen if one is using yarn workspaces and all scripts of the React application are declared on the workspace root package.

It seems that the problem lies on printHostingInstructions.js, as it tries to access deploy of scripts without checking if scripts exists first.

https://github.com/facebook/create-react-app/blob/915108b650635c28a96e0f5c9eedf672ee8ec0b1/packages/react-dev-utils/printHostingInstructions.js#L25

Did you try recovering your dependencies?

Yes

Which terms did you search for in User Guide?

build
deploy
PUBLIC_URL
homepage
scripts

Environment

npx: installed 91 in 5.921s

Environment Info:

  System:
    OS: Linux 5.3 Linux Mint 19.3 (Tricia)
    CPU: (8) x64 Intel(R) Core(TM) i7-4790K CPU @ 4.00GHz
  Binaries:
    Node: 8.17.0 - /usr/bin/node
    Yarn: 1.21.1 - ~/.yarn/bin/yarn
    npm: 6.13.4 - /usr/bin/npm
  Browsers:
    Chrome: 79.0.3945.88
    Firefox: 71.0
  npmPackages:
    react: ^16.12.0 => 16.12.0 
    react-dom: ^16.12.0 => 16.12.0 
    react-scripts: 3.3.0 => 3.3.0 
  npmGlobalPackages:
    create-react-app: Not Found

Steps to reproduce

Clone create-react-app
Run yarn
Run PUBLIC_URL=http://any.thing yarn build

Clone this repository
Run yarn
Run PUBLIC_URL=http://renato-bohler.github.io/my-app yarn build

Expected behavior

Build shouldn't fail.

Actual behavior

Build is failing with the message:

Cannot read property 'deploy' of undefined

Note that without setting PUBLIC_URL, the problem doesn't occur:

Reproducible demo

cra-build-issue, as mentioned on "Steps to reproduce", or create-react-app itself.