Jira issue originally created by user pschwisow:
DecimalType::convertToPHPValue should return NULL if the value in the database is NULL. This is similar to the issue with IntegerType that was fixed with #DDC-571.
The fix would be to replace
return (double) $value;
return is_null($value) ? null : (double) $value;
Comment created by @beberlei:
Issue was closed with resolution "Fixed"