realm-js: Crash on iOS 14.5 beta: Attempting to change configurable attribute of unconfigurable property

Expected Results

Not to crash.

Actual Results

Crashed on iOS 14.5 beta. All other iOS versions are fine.

If we don’t use Realm in JS, then everything is fine. But if we add one line to import Realm:

import Realm from 'realm';

It crashed with the following error: Attempting to change configurable attribute of unconfigurable property.

And crashed when running the following Object.defineProperties() in lib/extensions.js of realm-js:

Object.defineProperties(realmConstructor, getOwnPropertyDescriptors({
    _extendQueryBasedSchema(schema) {
        addSchemaIfNeeded(schema, realmConstructor.Permissions.Class);
        addSchemaIfNeeded(schema, realmConstructor.Permissions.Permission);
        addSchemaIfNeeded(schema, realmConstructor.Permissions.Realm);
        addSchemaIfNeeded(schema, realmConstructor.Permissions.Role);
        addSchemaIfNeeded(schema, realmConstructor.Permissions.User);
        addSchemaIfNeeded(schema, realmConstructor.Subscription.ResultSets);
    },

    // Creates the user agent description for the JS binding itself. Users must specify the application
    // user agent using Realm.Sync.setUserAgent(...)
    _createUserAgentDescription() {
        // Detect if in ReactNative (running on a phone) or in a Node.js environment
        // Credit: https://stackoverflow.com/questions/39468022/how-do-i-know-if-my-code-is-running-as-react-native
        try {
            var userAgent = "RealmJS/";
            userAgent = userAgent + require('../package.json').version + " (" + context + ", ";
            if (typeof navigator !== 'undefined' && navigator.product === 'ReactNative') {
                // Running on ReactNative
                const Platform = require('react-native').Platform;
                userAgent += Platform.OS + ", v" + Platform.Version;
            } else {
                // Running on a normal machine
                userAgent += process.version;
            }
            return userAgent += ")";
        } catch (e) {
            return "RealmJS/Unknown"
        }
    },
}));

Maybe due to some change in iOS 14.5 JavaScript core?

Steps to Reproduce

1.Setup a RN project and import realm-js 2.Run the App on iOS 14.5 beta.

Not sure whether it’s related to my RN version (0.59). But it all worked fine until the recently released iOS 14.5 beta. Tried Relam JS 5.0.5 and 6.1.5, both has the same issue.

Code Sample

import Realm from 'realm';

Version of Realm and Tooling

• Realm JS SDK Version: 5.0.5 and 6.1.5
• Node or React Native: RN 0.59.10
• Client OS & Version: iOS 14.5 beta
• Which debugger for React Native: None