SDC prop of `type: string` with empty string listed in its `enum` results in broken input UX

Overview

Discovered in ✨ Create a ComponentSource plugin for JS components Active .

Try using the sdc_test:my-cta SDC.

XB happily accepts it. But then creates an input UX that crashes, due to one of the allowed values for the target prop being ''.

Proposed resolution

Modify \Drupal\experience_builder\JsonSchemaInterpreter\SdcPropJsonSchemaType::computeStorablePropShape(): detect if '' is one of the values in the enum and if so, return NULL (to indicate this is not supported).

User interface changes

None.