First page of a guide crashes in certain circumstances

[joachim-n]

First page of a guide crashes with:

Drupal\Core\Render\Component\Exception\InvalidComponentException: [prev_title] NULL value found, but a string or an object is required. This may be because the property is empty instead of having data present. If possible fix the source data, use the |default() twig filter, or update the schema to allow multiple types.prev-next in Drupal\Core\Theme\Component\ComponentValidator->validateProps() (line 203 of core/lib/Drupal/Core/Theme/Component/ComponentValidator.php).

This was happening only in one theme, but not in another, but both themes had the localgov_guides_prev_next_block block.

I wasn't able to debug much further, as the block was removed in the theme where it caused the problem!

Maybe the prev_title in localgov_base/templates/block/guides-prev-next-block.html.twig needs a default value? That fixed the crash for me, but I don't see why if that's the fix, it wouldn't also crash in the other them!

[finnlewis]

Aha! Yep - I've been looking at this!

See localgovdrupal/localgov_subsites_extras#39

I've got a fix, PR coming.