Error: Using `babel-preset-react-app` requires that you specify `NODE_ENV` or `BABEL_ENV`

Created by: nicklayb

Can you reproduce the problem with latest npm?

yes

Can you still reproduce it?

yes

Description

When creating a new react app with create-react-app without doing anything, only running yarn start gives the following error :

Failed to compile.
./src/index.js
Module build failed: Error: Using `babel-preset-react-app` requires that you specify `NODE_ENV` or `BABEL_ENV` environment variables. Valid values are "development", "test", and "production". Instead, received: "undefined".
 (While processing preset: "/Users/nboisvert/Git/memberzone/node_modules/babel-preset-react-app/index.js")
    at Array.map (native)

Expected behavior

Run the template React app

Actual behavior

Displays :

Environment

Run these commands in the project folder and fill in their results:

1. npm ls react-scripts (if you haven’t ejected):

memberzone@0.1.0 /Users/nboisvert/Git/memberzone
└── react-scripts@1.0.6

2. node -v: v6.2.1
3. npm -v: 4.6.1

Then, specify:

1. Operating system: macOS Sierrra 10.12.5
2. Browser and version: Google Chrome Version 58.0.3029.110 (64-bit)

Reproducible Demo

Didn't add anything. Fresh install