I fall in an error due to assign null pointer to a std::string
In function Extractor::extract of MySQL backend we have function
val.assign(reinterpret_cast<const char*>(_metadata.rawData(pos)), _metadata.length(pos));
if the value extracted from _metadata.rawData(pos) return reinterpret_cast<const unsigned char*>(_row[pos].buffer); is null than the assign crash