[ECO-5616] Change non spec errors

[maratal]

Closes #438

• failedToResolveSubscriptionPointBecauseChannelSerialNotDefined: renamed since channelSerial checked first. Introduced error code used in JS - 102_110;
• failedToResolveSubscriptionPointBecauseChannelFailedToAttach: changed error code to 102_112 (roomInInvalidState), JS doesn't throw anything and just waits for channel attach event. Proposed spec for throwing an error with 102_112 code;
• noItemInResponse: changed error code to 404 and proposed spec for that;
• failedToGetPaginatedResult: renamed and added full error info taken from realtime, JS also throws error with values from realtime. Am not sure what to do with badRequest here, probably it's fine to leave it (or internalServerError maybe?);
• headersValueJSONDecodingError and jsonValueDecodingError are JSON parser errors and probably should stay with badRequest.

Removed unused MessagesError enum.

Proposed specs: ably/specification#401

[coderabbitai]

Important

Review skipped

Draft detected.

Please check the settings in the CodeRabbit UI or the .coderabbit.yaml file in this repository. To trigger a single review, invoke the @coderabbitai review command.

You can disable this status message by setting the reviews.review_status to false in the CodeRabbit configuration file.

✨ Finishing touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment
• Commit unit tests in branch 438-non-specified-errors

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

_{Comment @coderabbitai help to get the list of available commands and usage tips.}