When the skip-trivial-records verb is in the then-chain, the CSV/TSV
record-readers now silently skip trivial (all-fields-empty) input lines
-- notably blank lines at the end of a CSV file -- instead of raising a
fatal header/data length mismatch. The user has explicitly asked for
trivial records to be skipped, so mlr now exits 0 in this case.
The verb's CLI parser sets a new ReaderOptions.SkipTrivialRecords flag,
which the CSV and TSV readers consult only on the would-be-fatal
mismatch path, so:
* Behavior without the verb is unchanged: blank lines still error.
* Genuinely ragged non-trivial records still error even with the verb.
* --allow-ragged-csv-input behavior is unchanged.
Fixes#1535.
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
