No detailed info about errors may be shown for misconfigured cards

[ildar170975]

Since 2025.6 - if a card is wrongly configured, it shows a brief “Configuration error” message:

then a detailed info in editor & a preview:

and also a detailed info in Edit mode:

But in a yaml-based dashboard you will always see a brief “Configuration error” message. So, to see a possible explanation, a user needs to copy a code from yaml, paste it into UI editor (along with processing possibly using anchors, “includes”, secrets, decluttering templates, …).
Not a best way.

In case of custom cards, a user will not see a detailed info in ANY case - both in a storage & yaml modes.
Test code:

type: entities
entities:
  - entity: sun.sun
  - type: custom:multiple-entity-row
    entity1: sun.sun

In 2025.1 we see this:

In 2025.6.3:

There should be a documented way (API, guidelines, …) for 3rd party developers to pass errors/warnings info Frontend. Otherwise custom cards are not as “friendly” as they were.

Although there could be some exceptions - this is a custom card:

But this is really an exception - in many cases this particular card started displaying only that brief "Configuration error" message and thus there is no chance to get a detailed info to fix an issue.