add eligibility check to children card fields in order to throw more meaningful error messages when card fields aren't eligible

Author: gusveloso

src/zoid/card-fields/component.jsx

@@ -216,6 +216,15 @@ export const getCardFieldsComponent: () => CardFieldsComponent = memoize(
           },
         },
 
+        eligible: ({ props }) => {
+          // Prevent child field from being eligible if parent is not eligible
+          // Parent props will be empty as eligibility is checked before props are set
+          if (Object.keys(props.parent.props).length === 0) {
+            return { eligible: false };
+          }
+          return { eligible: true };
+        },
+
         props: {
           type: {
             type: "string",