Configurable rule fails with unclear error message

[tatomyr]

Describe the bug

To Reproduce Steps to reproduce the behavior:

1. Given this redocly.yaml file

rules:
  rule/test:
    subject:
      type: Operation
      property: summary

3. And any OpenAPI file(
4. Run this command with these arguments... redocly lint
5. See error

Expected behavior

The error should reflect that the assertsion section is missing.