When switching from Vaadin 14.5.5 to Vaadin 14.6.4 (any minor version of Vaadin 14.6) next error appears in console:
Uncaught ReferenceError: tinymce is not defined
…
Object…/target/frontend/frontend/tinymce_addon/tinymce/themes/silver/theme.js (vaadin-bundle-a1a9c9ac6f496b1ce541.cache.js:4397)
at webpack_require (vaadin-bundle-a1a9c9ac6f496b1ce541.cache.js:20)
…