**Describe the bug**
https://clickhouse-test-reports.s3.yandex.net/19702/c74631c650b42e4d107254a03bd82c2c2913039b/fuzzer_msan/server.log

Most likely introduced here: #11006
{
    return prev_reader ? prev_reader->isReadingFinished() : stream.isFinished();
}
size_t MergeTreeRangeReader::numReadRowsInCurrentGranule() const
{
    return prev_reader ? prev_reader->numReadRowsInCurrentGranule() : stream.numReadRowsInCurrentGranule();
}
size_t MergeTreeRangeReader::numPendingRowsInCurrentGranule() const