HPCC-10953 FileSpray.UploadFile exceptions are not being displayed

Fixes HPCC-10953

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #5705 from GordonSmith/HPCC-10953

HPCC-10953 FileSpray.UploadFile exceptions are not being displayed

Reviewed-By: Kevin Wang <kevin.wang@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>