Please give us a description of what happened.

Getting a blank meta box when both Classic Editor plugin and OneSignal Push Notifications plugins are activated.

Getting the following console errors:

The meta box works fine when using Gutenberg and OneSignal Push notifications. Issue only happens when using the Classic Editor plugin and OneSignal Push notifications.

Please describe what you expected to happen and why.

I expect the meta box to show up.

How can we reproduce this behavior?

1. Install and activate the latest Classic Editor plugin
2. Install and activate the latest OneSignal Push Notifications
3. Create a new post or a page.
4. Meta Box does not load and throws a js error.

Technical info

• If relevant, which editor is affected (or editors):

• Classic Editor
• Gutenberg
• Classic Editor plugin

• Which browser is affected (or browsers):

• Chrome
• Firefox
• Safari
• Other

Used versions

• WordPress version: 5.1.1
• Yoast SEO version: 9.7 and 10.0
• Classic Editor plugin version: 1.4
• OneSignal Push Notifications: 1.16.15

• Tested with theme: Twenty Sixteen