Allow raising errors from within a custom whatever

[Morriz]

Prerequisites

• [x] I have read the documentation;

Description

It should be possible to raise an error from within a custom component. Currently it seems that only schema validation errors are taken into account, but there are other potential errors:

• a value is deemed invalid by the component, not the schema. Example:
  • a code editor that determines the (schemaless) content has a valid shape.

Expected behavior

An extra function passed in, like raiseErrors, that accepts an array of error strings.

[cdolek]

Any progress on this? Such a valuable feature to add since it will help with creating many customizations.

[ericalli]

+1, I'd also find this feature super valuable.

[mc-smarthelio]

+1