@defer.inlineCallbacks
    def open_spider(self, spider):
        self.slot = Slot()
        yield self.itemproc.open_spider(spider)
Ensure that "value" has a type that matches the type of the column.
dataset/ETHPy150Open scrapy/scrapy/scrapy/core/scraper.py/Scraper.open_spider--crossover with--dataset/ETHPy150Open viewfinderco/viewfinder/backend/db/schema.py/_Value._CheckType