Laravel - Error when adding values to select PDOException(code: 42000): SQLSTATE[42000]

Question

I get an error when I try to add new table field

(PDOException(code: 42000): SQLSTATE[42000]: Syntax error or access violation: 1055 
Expression #17 of 
SELECT list is not in GROUP BY clause and contains nonaggregated column 'c.color_slug' 
which is not functionally dependent on columns in GROUP BY clause; this 
is incompatible with sql_mode=only_full_group_by

This works:

$products = DB::table('product_color_relations')
                ->select( 'p.product_slug' , 'p.product_id' , 'p.product_slug' , 'p.product_name' , 'p.product_ref' , 'p.product_img' , 'p.product_price' , 'p.product_sale_price' , 'p.product_stock' , 'p.product_unit' , 'p.created_at')
                ->join('colors as c' , 'c.color_id' , '=' , 'product_color_relations.r_color_id')
                ->join('products as p' , 'p.product_id' , '=' , 'product_color_relations.r_product_id')
                ->groupBy('product_color_relations.r_product_id')
                ->havingRaw('MAX(`product_color_relations`.`r_color_id`) = MIN(`product_color_relations`.`r_color_id`) AND MIN(c.color_slug) = ? ' , [ $var['v'] ] )
                ->get();

this doesn't:

$products = DB::table('product_color_relations')
                ->select( 'p.product_slug' , 'p.product_id' , 'p.product_slug' , 'p.product_name' , 'p.product_ref' , 'p.product_img' , 'p.product_price' , 'p.product_sale_price' , 'p.product_stock' , 'p.product_unit' , 'p.created_at' , 'c.color_slug')
                ->join('colors as c' , 'c.color_id' , '=' , 'product_color_relations.r_color_id')
                ->join('products as p' , 'p.product_id' , '=' , 'product_color_relations.r_product_id')
                ->groupBy('product_color_relations.r_product_id')
                ->havingRaw('MAX(`product_color_relations`.`r_color_id`) = MIN(`product_color_relations`.`r_color_id`) AND MIN(c.color_slug) = ? ' , [ $var['v'] ] )
                ->get();

Difference between them that I added to the select method this field: 'c.color_slug' I can't understand why I'm getting this error. In plain php it works.

$sql = "select `p`.`product_slug`, `p`.`product_id`, `p`.`product_slug`, `p`.`product_name`, `p`.`product_ref`, `p`.`product_img`, `p`.`product_price`, `p`.`product_sale_price`, `p`.`product_stock`, `p`.`product_unit`, `p`.`created_at` , c.color_slug from `product_color_relations` inner join `colors` as `c` on `c`.`color_id` = `product_color_relations`.`r_color_id` inner join `products` as `p` on `p`.`product_id` = `product_color_relations`.`r_product_id` group by `product_color_relations`.`r_product_id` having MAX(`product_color_relations`.`r_color_id`) = MIN(`product_color_relations`.`r_color_id`) AND MIN(c.color_slug) = 'white'"