fix: propagate json.Unmarshal error in mysql rowDataConverter

[vedant21-oss]

Resolves #6699

The rowDataConverter in the MySQL datastore now returns an error that bubbles up through Iterator.Next() to handle silent json.Unmarshal failures.

[eeshaanSA]

Hey @vedant21-oss, thanks for this. Do you have any logs that can support this?

Did anyone try reproducing?

@rahulshendre @Ayushmore1214

[vedant21-oss]

Hey @eeshaanSA, thanks for the review!

I just updated the PR to include a unit test that explicitly reproduces this behavior in pkg/datastore/mysql/iterator_test.go.

Without the fix, the JSON unmarshaling silently failed, and an empty/partial object was returned. With this fix, running the tests explicitly captures the error. Here is the log output from the new testcase simulating invalid JSON data from the database:

=== RUN TestData/invalid_json_data
iterator_test.go:152: Expected error caught: unexpected end of JSON input
--- PASS: TestData/invalid_json_data (0.00s)

The unmarshal error is now properly propagated up to the caller instead of being swallowed. I've force-pushed the test coverage alongside the fix.

[rahulshendre]

Reproduced locally. All tests pass, invalid_json_data catches the error correctly.
One note:
Cursor() error path (lines 62-65 of iterator.go) isn't covered by any test case, it returns nil.
@vedant21-oss i think we should add a case there too

[rahulshendre]

hey @vedant21-oss, any updates on this one 👀