Error when include specific customers/products checked, but no list provided.

[lat9]

When you check "Only include specific Customer IDs (comma separated list)" but provide no customers or "Only include specific Product IDs (comma separated list) " and provide no products, a PHP Fatal Error is logged. Corrected by #7 (thanks, @scottcwilson).

[15-Mar-2019 16:35:11 America/Chicago] Request URI: /my_site/admin/stats_sales_report.php?date_preset=last_week&start_date=&end_date=&date_target=purchased&date_status=1&prod_includes=&doCustInc=on&cust_includes=&payment_method=&payment_method_omit=&current_status=&manufacturer=&timeframe=day&timeframe_sort=desc&detail_level=order&li_sort_a=oID&li_sort_order_a=desc&li_sort_b=oID&li_sort_order_b=asc&output_format=display, IP address: ::1
#1  trigger_error() called at [/Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php:167]
#2  queryFactory->show_error() called at [/Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php:139]
#3  queryFactory->set_error() called at [/Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php:266]
#4  queryFactory->Execute() called at [/Users/scott/Sites/my_site/admin/stats_sales_report.php:753]

[15-Mar-2019 16:35:11 America/Chicago] PHP Fatal error:  1064:You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near '' at line 1 :: select distinct c.customers_firstname, c.customers_lastname from zen_customers c where customers_id =  ==> (as called by) /Users/scott/Sites/my_site/admin/stats_sales_report.php on line 753 <== in /Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php on line 167
[15-Mar-2019 16:35:11 America/Chicago] PHP Stack trace:
[15-Mar-2019 16:35:11 America/Chicago] PHP   1. {main}() /Users/scott/Sites/my_site/admin/stats_sales_report.php:0
[15-Mar-2019 16:35:11 America/Chicago] PHP   2. queryFactory->Execute() /Users/scott/Sites/my_site/admin/stats_sales_report.php:753
[15-Mar-2019 16:35:11 America/Chicago] PHP   3. queryFactory->set_error() /Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php:266
[15-Mar-2019 16:35:11 America/Chicago] PHP   4. queryFactory->show_error() /Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php:139
[15-Mar-2019 16:35:11 America/Chicago] PHP   5. trigger_error() /Users/scott/Sites/my_site/includes/classes/db/mysql/query_factory.php:167