fix: update script, update package.json

Changes:

- Revert 'if-nodejs-pr-testing.yml' to original condition.

- Update 'package.json', changed "test" field to include the JSON Schema validation.

- Change naming convention, from 'validate-schema' to 'validate:schema'.

- Modify error handling 'catch' block on line 79 to terminate script if
  the schema is not valid.

- Applied suggestion from: #452 (review)

.github/workflows/if-nodejs-pr-testing.yml

@@ -75,7 +75,4 @@ jobs:
         run: npm run lint --if-present
       - if: steps.packagejson.outputs.exists == 'true'
         name: Run release assets generation to make sure PR does not break it
-        run: npm run generate:assets --if-present
-      - if: steps.packagejson.outputs.exists == 'true'
-        name: Run JSON Schema Validator
-        run: npm run validate-schemas
+        run: npm run generate:assets --if-present