In the print_all_bug_page_excel.php file, the function "get_field_names" is used two times but only the second one is necessary:

#settings for choosing the fields to print

get the fields list
$t_field_name_arr = get_field_names();

...

#settings for choosing the fields to print
# get the fields list
$t_field_name_arr = get_field_names();
$field_name_count = count( $t_field_name_arr );