feat: trigger oobErrorNoTarget for missing oob swap targets

[stenehall]

Description

Currently the parent of an oob-swap will not get an oobErrorNoTarget event when added to the hxOn event trigger.

Given the following code:

<ul hx-ext="ws" ws-connect="/ws" id="hosts" hx-on:htmx:oob-error-no-target="console.log('error triggered')></ul>

And the following message from the server

<tr id="some-id" hx-swap-oob="outerhtml:#none-existing-id">

Nothing will happen. But with this change the console.log will run.

Corresponding issue:

Testing

This was tested manually using a very similar code to the above. I was trying to figure out where a test would fit in hx-swap-oob.js but it wasn't immediately obvious to me. If you think the change is correct I will spend more time on figuring out a test for it.

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

[scrhartley]

For existing projects that were already using this on body as a general error mechanism,
it seems that it will now trigger multiple times due to event bubbling.
Additionally, if the target is body, will it trigger twice, once for the general event and once for the settle target event?

[stenehall]

For existing projects that were already using this on body as a general error mechanism, it seems that it will now trigger multiple times due to event bubbling. Additionally, if the target is body, will it trigger twice, once for the general event and once for the settle target event?

Good questions. I'm not entirely sure how it will behave in relation to event bubbling nor body. But, I can spend a bit of time creating tests for this. If the general idea seems correct here.

To me the current behavior seems wrong, but the change might be a breaking change.