Getting cryptic error if the file to return ENV object return null or {} instead

I have solved the issue myself but I thought it can be better.

It is good that it throws an error about it but the cryptic error message like this is not helping
```
remote: Module build failed: TypeError: /tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/components/BuildTeam.js: Cannot convert undefined or null to object
remote: at PluginPass.UnaryExpression (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-plugin-transform-define/lib/index.js:34:27)
remote: at newFn (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/visitors.js:276:21)
remote: at NodePath._call (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/path/context.js:76:18)
remote: at NodePath.call (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/path/context.js:48:17)
remote: at NodePath.visit (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/path/context.js:105:12)
remote: at TraversalContext.visitQueue (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/context.js:150:16)
remote: at TraversalContext.visitSingle (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/context.js:108:19)
remote: at TraversalContext.visit (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/context.js:192:19)
remote: at Function.traverse.node (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/index.js:114:17)
remote: at NodePath.visit (/tmp/build_43fb00b7ca544651b6eb4730c0d0ad94/node_modules/babel-traverse/lib/path/context.js:115:19)
```
This throws when the page it is saying at fault does not even use any of the variables supposed to be defined in env, but simply uses Unary Expression like "typeof".

Perhaps make the error clearer if the env passed in .babelrc is returning {} or null?

Thanks

Commencez par examiner la configuration ENV de .babelrc et le chemin défaillant dans babel-plugin-transform-define/lib/index.js. Reproduisez le cas où ENV renvoie null ou {}, y compris avec un fichier qui utilise uniquement une expression unaire telle que typeof ; le travail est terminé lorsque l’échec indique que la valeur de ENV est invalide au lieu d’exposer le TypeError cryptique.

Rédigé par le modèle d'indexation à partir du texte de l'issue.