Fix broken oob swap error handling.

[Wohlie]

Description

For missing target on oob swap the event htmx:oobErrorNoTarget must be triggered (see https://htmx.org/events/#htmx:oobErrorNoTarget)

Corresponding issue:

Testing

1. Added a new test
2. via npm run test

Checklist

• I have read the contribution guidelines
• I have targeted this PR against the correct branch (master for website changes, dev for
  source changes)
• This is either a bugfix, a documentation update, or a new feature that has been explicitly
  approved via an issue
• I ran the test suite locally (npm run test) and verified that it succeeded