Star imports from react-native cause "Native module cannot be null" error on startup

[dphilipson]

Description

As the title says. If React Native is star-imported, e.g.

import * as RN from 'react-native';

then the app shows a "Native module cannot be null" redbox on startup and fails to load. Similarly, Jest tests fail with the same error.

Reproduction

I can reproduce this by taking the starting project from react-native init AwesomeProject and adding the following line to index.ios.js.

import * as RN from 'react-native';

The app then shows the following error on startup:

Likewise, npm test fails with the following error:

 FAIL  __tests__/index.ios.js
  ● Test suite failed to run

    Invariant Violation: Native module cannot be null.

      at invariant (node_modules/fbjs/lib/invariant.js:44:15)
      at Linking.NativeEventEmitter (node_modules/react-native/Libraries/EventEmitter/NativeEventEmitter.js:32:1)
      at new Linking (node_modules/react-native/Libraries/Linking/Linking.js:119:141)
      at Object.<anonymous> (node_modules/react-native/Libraries/Linking/Linking.js:191:16)
      at Object.get Linking [as Linking] (node_modules/react-native/Libraries/react-native/react-native.js:91:22)
      at _interopRequireWildcard (index.ios.js:14:233)
      at Object.<anonymous> (index.ios.js:14:4)

Here attached is a project demonstrating this, which was produced by taking the react-native init project and adding the single line given above.

ImportRepro.zip

Solution

This seems to occur because Babel transforms the above code into

var _reactNative = require("react-native");
var RN = _interopRequireWildcard(_reactNative);

function _interopRequireWildcard(obj) {
    if (obj && obj.__esModule) {
        return obj;
    } else {
        var newObj = {};
        if (obj != null) {
            for (var key in obj) {
                if (Object.prototype.hasOwnProperty.call(obj, key))
                    newObj[key] = obj[key];
            }
        }
        newObj.default = obj;
        return newObj;
    }
}

I'm guessing that those property accesses are triggering initialization on some of the native modules, which is failing if they're not linked. Worth noting is that using import RN from 'react-native' instead works fine.

I dunno how to fix it. I just talk about things.

Additional Information

• React Native version: 0.40.0
• Platform: iOS, and in tests. I haven't tried running on Android, but I would guess it's there too.
• Operating System: OSX 10.11.6

[quantuminformation]

We just came across this issue today in a fresh install of RN. I think there is some manual linking needed ?

[hramos]

Hi there! This issue is being closed because it has been inactive for a while. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. Either way, we're automatically closing issues after a period of inactivity. Please do not take it personally!

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