fix: address beacon dispose error, also indexed-picker bug

[paulmck21]

• beacon needs to be disposed on leaving the editor, but sometimes it doesn't exist 😱

[TeamKano]

Coverage summary
Statements	29.39%	1999/6801
Branches	19.96%	203/1017
Functions	29.48%	653/2215
Lines	29.29%	1932/6596

From Jenkins: kano-code/PR-1778