Ignore blank lines when reading JSONL

[biefan]

Summary

This makes read_jsonl() tolerate blank lines in JSONL input.

Problem

read_jsonl() currently does a direct json.loads(line) for every line in the file.

That means a JSONL file with an empty line or a whitespace-only separator fails immediately with JSONDecodeError, even when every non-empty line is valid JSON.

In practice, blank lines are common in generated or hand-edited JSONL files, especially at the end of a file or between entries during review.

Fix

Skip blank / whitespace-only lines before decoding:

json.loads(line) for line in file if line.strip()

This preserves the existing behavior for valid JSONL records while making the reader robust to common formatting noise.

Tests

Added regression coverage for a JSONL stream containing a blank line between two valid entries.

Validation command:

.venv/bin/pytest tests/unit/common/test_json_helper.py -q

Validation result:

1 passed in 0.01s