Thanks for this report. Now I see that empty param causes has some more implications than just an error in edit box.
I would like to clarify some "how it works" here.
Customers is a Contact or Company field, so it allows you to choose between a Contact and Company. It's a special type defined by the CRM/Contacts module. It uses own QFfield and display callback functions - they create a select and performs ajax searches for the supplied text. Also there is a difference how the data is stored. This field stores Contact/Company indicator as a prefix (P:13 -- person[contact] with id=13, C:4 -- company with id=4).
So this field type doesn't need a param itself, because it has defined those callbacks, that operate on a custom data. But as you can see it's screwed up in some places, because sometimes EPESI reads that it's multiselect/select field type and doesn't bother that it has custom callbacks. It just treats this field as a regular multiselect/select type and you'll get an error.
If you've filled in the param as stated by Janusz in this post, then you'll get the search box, but it won't work.
To search a records RB has to know the relation, that is provided in param for multiselect/select fields. You've provided a relation that is wrong. Because now RB is trying to find a Contact where id is equal to P:13 and there is no such records. So searching by this field will always return no results.
So I think that (until search doesn't work) no search box is a better than not working search box.
Regards,
Adam
