_createSuper is not defined

Bug Report

Current Behavior if you define two class in one js file, will error Uncaught ReferenceError: _createSuper is not defined

Input Code

• REPL or Repo link if applicable:

class A extends React.Component {
}
export default class B extends React.Component {
}

Expected behavior/code update dependencies

Environment

• @babel/plugin-transform-classes@7.9.2

Possible Solution

Additional context/Screenshots

[nicolo-ribaudo]

Can you check what npx nls why @babel/helpers prints?

Also, those helpers aren’t called from babelHelpers.createSuper probably because Babel doesn’t know which helpers it can safely use from the babelHelpers object (it must assume that it is ^7.0.0). You can pass the "helperVersion": "^7.9.0" option to the plugin if you want to tell Babel that you are using an up-to-date babelHelpers object.

[nicolo-ribaudo]

@ulrichb This bug should only happen when using @babel/core <7.5.5, but CRA uses 7.9.0.

Could you run npx nls why @babel/core and post the output?