fix(cursor): return NotEnoughData

[loyd]

Summary

It fixes the regression introduced in #169.
Previously, the cursor checked if unhandled bytes were left.
Return this behavior to detect schema mismatch.

Closes #185

Checklist

Delete items not relevant to your PR:

• Unit and integration tests covering the common scenarios were added
• A human-readable description of the changes was provided so that we can include it in CHANGELOG later
• For significant changes, documentation in README and https://github.com/ClickHouse/clickhouse-docs was updated with further explanations or tutorials