Fix options randomly despawning instantly when they appear

[janhohenheim]

The reason is as follows:

• When the dialog is done, a DialogueCompleteEvent is sent
• Some processes check the DialogueCompleteEvent to despawn stuff, consuming the event
• However, these checks don't always happen. We might despawn for other reasons.
• Thus, DialogueCompleteEvent might accumulate
• Opening a dialog a second time will consume the DialogueCompleteEvent of the last dialog, triggering weird behavior.