Fix JsonColumnType

[DarthRevanXX]

The bug when you are reading from database null give you error so cannot deserialize, updated version

fun <T : Any> Table.json(name: String, serialize: (Any) -> String, deserialize: (String) -> Any): Column<T> =
    registerColumn(name, JsonColumnType(serialize, deserialize))

class JsonColumnType(
    private val serialize: (Any) -> String,
    private val deserialize: (String) -> Any
) : ColumnType() {
    override fun sqlType() = "JSON"

    override fun setParameter(stmt: PreparedStatementApi, index: Int, value: Any?) {
        super.setParameter(
            stmt,
            index,
            value.let {
                PGobject().apply {
                    this.type = sqlType()
                    this.value = value as String?
                }
            }
        )
    }

    override fun valueFromDB(value: Any): Any {
        if (value is PGobject) {
            val jsonValue = value.value
            if (!jsonValue.isNullOrBlank()) {
                return deserialize(jsonValue)
            }
        }
        return value
    }

    override fun valueToString(value: Any?): String {
        if (value == null) {
            return "NULL"
        }
        return "'${serialize(value)}'"
    }

    override fun readObject(rs: ResultSet, index: Int): Any? {
        val stringValue = rs.getString(index)
        return if (stringValue != null) {
            deserialize(stringValue)
        } else {
            null
        }
    }

    override fun notNullValueToDB(value: Any): String = serialize(value)
}