Bugfix: Resolves PHP notices when the prefix element is undefined.

[amcgowanca]

No description provided.

[phenaproxima]

Nice little fix. @amcgowanca, if you will add a comment explaining what you're fixing -- just a sentence or two, for posterity -- I think this is OK to merge.

[phenaproxima]

Although, one thing does give me pause here: we're extending Entity Browser's widget, which means that we should be able to rely on their render array having a certain structure, and having certain keys. So now I'm not 100% sure this is something we should be fixing. At the very least, we should be aware of the conditions under which the prefix is not set, rather than just working around the possibility of it not being set.

[amcgowanca]

@phenaproxima -

Ha, my apologies for not adding a comment. I was pushing up various PRs all morning and this one had slipped through the crack for a comment. I am going to re-test so I can provide exact scenario and circumstances where I ran into the issue this morning. I'll mark this as closed if it is in fact not relevant from what I uncover when I take another look. Thanks.

[danepowell]

We started seeing these errors after upgrading to Lightning 2.1.4, presumably because of this commit: 7998fcc

However they've been very difficult to reproduce consistently. The only thing I know for sure is that they appear on the node_add form for content types containing media reference / entity browser fields.

[balsama]

@danepowell Can you confirm that you have patch 10 from 2877751 applied to Entity Browser?

EntityReferenceBrowserWidget::displayCurrentSelection populates current. That patch adds the last line in the snippet below to displayCurrentSelection - so I can't see any way ['current']['#prefix'] could not be populated if that patch is applied.

    return [
      '#theme_wrappers' => ['container'],
      '#attributes' => ['class' => ['entities-list']],
      '#prefix' => '<p>' . $this->getCardinalityMessage($entities) . '</p>',
...

[danepowell]

Yep that patch is definitely applied.

[amcgowanca]

@balsama , @phenaproxima , @danepowell :

This is the stack trace from the PHP notice that is printed when I receive the issue. Just encountered it again this morning. I should also add that this is happening on both the Field UI (when the default value/widget is rendered) screen and entity edit forms in which the field is being used.