Зробив перевірку на this.$refs.dropdown та обернув в if. Додал в CHANGELOG.md
воспроизвести получается на медленных устройствах (например A8-7600, 2 ядра 4 потока) либо очень активно кликая
fixed Uncaught TypeError: Failed to execute 'observe' on 'MutationObserver': parameter 1 is not of type 'Node'
Occures on slow client computers.
Reason: setTimeout
with 0 schedule the callback to be run asynchronously, after the shortest possible delay.
during this time this.visible might become = false and value of this.$refs.dropdown will be undefined because of v-if on dropdown
Alexander Kolesnikov (21eb5b46) at 16 May 18:11
fix for: "Uncaught TypeError: Failed to execute 'observe' on 'Mutat...