Problem

renderers/web_core/src/v0_9/basic_catalog/components/basic_components.ts (line 440) declares SliderApi.step, but the field does not exist in specification/v0_9/json/basic_catalog.json, which uses unevaluatedProperties: false. A payload with step passes WebCore validation but fails canonical spec validation and is silently ignored by React, Lit, and Flutter.

json

source code

Fix

Since v0.9 is frozen, remove step from basic_components.ts and slider.component.ts. If the field is wanted, formally add it to v0.10.