ARROW-17858: [C++] Compilating warning in arrow/csv/parser.h (#14445)
ARROW-17858: [C++] Compilating warning in arrow/csv/parser.h (#14445)

This PR modifies the `DecorateWithRowNumber` method in the `DataBatch` class to return an unknown error to avoid getting a compilation warning.

Lead-authored-by: Sanjiban Sengupta <06f0d70538f536e4c1c90ac3e2e7b0862562baf5@gmail.com>
Co-authored-by: Antoine Pitrou <9359a4d812173b65a3a0094cd86363e79731a3c2@python.org>
Signed-off-by: Antoine Pitrou <9359a4d812173b65a3a0094cd86363e79731a3c2@python.org>
kou/arrow,apache/arrow,kou/arrow,apache/arrow,apache/arrow,apache/arrow,apache/arrow,apache/arrow,kou/arrow,apache/arrow,kou/arrow,apache/arrow,kou/arrow,kou/arrow,kou/arrow,kou/arrow,kou/arrow,apache/arrow,apache/arrow,kou/arrow,kou/arrow,apache/arrow,apache/arrow,apache/arrow,apache/arrow,kou/arrow,kou/arrow,kou/arrow