presto-main/src/main/java/io/prestosql/type/UnknownType.java/UnknownType/getBoolean
class UnknownType:    @Override
    public boolean getBoolean(Block block, int position)
    {
        // Ideally, this function should never be invoked for unknown type.
        // However, some logic rely on having a default value before the null check.
        checkArgument(block.isNull(position));
        return false;
    }