I’ve upgraded to version 5.0.2 and now I can’t seem to create a new post.

I select Add New Post from the menu and a second after the page loads, a popup appears:

The editor has encountered an unexpected error. Attempt Recovery | Copy Post Text | Copy Error

If I select Copy Error I see the following information:

TypeError: Cannot read property 'show_ui' of undefined
    at https://www.bradbox.com/blog/wp-includes/js/dist/editor.min.js?ver=9.0.6:55:240816
    at i (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/lodash.min.js?ver=4.17.11:6:91)
    at An.filter (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/lodash.min.js?ver=4.17.11:99:338)
    at https://www.bradbox.com/blog/wp-includes/js/dist/editor.min.js?ver=9.0.6:55:240781
    at ph (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.6.3:97:88)
    at eg (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.6.3:125:307)
    at fg (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.6.3:126:168)
    at wc (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.6.3:138:237)
    at fa (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.6.3:137:115)
    at gg (https://www.bradbox.com/blog/wp-includes/js/dist/vendor/react-dom.min.js?ver=16.6.3:135:196)

Please help!