TypeError: this.$element.querySelector(...).previousElementSibling is null

Sentry Issue: FRONT-87

TypeError: this.$element.querySelector(...).previousElementSibling is null
  at clean (./src/app/common/components/editors/plugins/buttons.plugin.ts:159:30)
  at apply (./src/app/common/components/editors/plugins/buttons.plugin.ts:311:10)
...
(5 additional frame(s) were not displayed)