Be more helpful if there's no bundle to choose from

+ screenshot

typo

This is an issue with entity reference fields. Moving accordingly.

To a certain extent, yes, unless we're shipping media module with a preconfigured media type, as we do with content types.
While I suggested "splitting off to a separate issue against entity_reference," it's probably fine if we're moving the whole issue there.

I was surprised not to find a bug filed against entity_reference or taxonomy (where the same should occur, though its users might be slightly more experienced or it might be slightly more obvious to create a taxonomy first), so let this one be the place for a generic solution.

As long as we're not adding strings, the Usability bug should be able to go into 8.6.x, if I'm not wrong.

Generalized, so it refers to all kinds of target bundles.

Here's a working patch and some screenshots:

No reroll necessary, it was simply the wrong patch. Here's the correct one.

Same screenshots again:

Also, thanks for your invitation! I hope I can be with you next Tuesday! :)

One more time... sorry for the noise.

Thanks for reviewing!

The whole code block in question is however already wrapped in
if ($entity_type->hasKey('bundle')) {
which should suffice. Am I missing something?

I manually tested this with:

• content entity types that are defining a bundle entity type
  • with existing bundles
  • without existing bundles
• (custom) content entity types that aren't defining a bundle entity type
• config entity types

and in all cases it worked fine.

Another minor oddity:
+ $url = Url::fromUserInput($collection, ['query' => ['destination' => \Drupal::request()->getRequestUri()]]);
I'm adding the current Uri as destination to make sure the user returns to complete setting up the entity reference field once they created a bundle. However, the destination gets lost with the second click. Unsure if there's a way to make it stick or if I should remove it.

For some reason, the particular test that failed in #13, passes locally. Fixed a probably unrelated bug, and am rerunning the test now to see if the the test failure is still there.

1.

Content entity types can also have bundles that are provided by a hook_entity_bundle_info() implementation, and not by a config entity type.

Ah okay, I missed that. Thanks for pointing me to it!

Really, all that's needed if to wrap that code in a condition that checks for a non-NULL value of getBundleEntityType() :)

That would lead to an insanely long if-clause, unless broken down into several lines. However, if $bundle_entity_type_id is NULL, this will also be NULL:
$bundle_entity_type = $this->entityTypeManager->getDefinition($bundle_entity_type_id);
So instead I'm checking for a non-NULL value of $bundle_entity_type, just one step later. This way, we can also be even more sure it contains a valid EntityTypeInterface object to work with.

2.

About the destination stuff, you could also try this:

Thanks, this is a nice shortcut I rolled in. However it doesn't make any difference in regard to the destination surviving the next click. Leaving the non-working destination in though, as the user should really be redirected back to where they came from. Either I missed something and there's a proper way to make it work, or there's currently no way to make it work, then we need to solve this generically.

3.
For some reason, Drupal\Tests\field\FunctionalJavascript\EntityReference\EntityReferenceAdminTest::testFieldAdminHandler still tests green locally, while failing with the testbot. I guess this shouldn't be the case and needs further investigation.