fix: return on invalid ref pointer in remove-unused-components for OAS2

[DmitryAnansky]

What/Why/How?

Return on invalid ref pointer in remove-unused-components for OAS2.

Reference

#2286

Testing

Screenshots (optional)

Check yourself

• Code changed? - Tested with Redoc/Realm/Reunite (internal)
• All new/updated code is covered by tests
• New package installed? - Tested in different environments (browser/node)
• Documentation update considered

Security

• The security impact of the change has been considered
• Code follows company security practices and guidelines

[changeset-bot]

⚠️ No Changeset found

Latest commit: 0231338

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes changesets to release 3 packages

Name	Type
@redocly/openapi-core	Patch
@redocly/cli	Patch
@redocly/respect-core	Patch

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[github-actions]

Command	Mean [s]	Min [s]	Max [s]	Relative
redocly lint packages/core/src/benchmark/benches/rebilly.yaml	1.459 ± 0.027	1.420	1.515	1.00
redocly-next lint packages/core/src/benchmark/benches/rebilly.yaml	1.482 ± 0.014	1.464	1.510	1.02 ± 0.02