When an exception is thrown now result is reported. The script accumulating the results then detects this and the serializer is excluded from the results. However there is output at system.err reporting this. However maybe there is a bug in this handling (e.g. exception caught and results reporte despite having an error)
# find files with no numbers => errors
echo ""
echo "====================================================================================="
echo "errors:"
find ./results/tmp/. -print -type f -name "*.txt" -exec tail -1 {} \; | grep -B 1 create
echo "====================================================================================="
echo ""