[BUG] WSOD on Media page

[rosiel]

I installed Embargoes, and then found that I could not access the Media page at admin/content/media. It turns out to happen because I had a media type that didn't have any entity reference fields (i.e. wasn't set up for Islandora).

The error in Drupal's logs was:

Drupal\Core\Database\DatabaseExceptionWrapper: SQLSTATE[42000]: Syntax     
error or access violation: 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 4: SELECT "base_table"."vid" AS        
"vid", "base_table"."nid" AS "nid"                                         
 FROM                                                                       
"node" "base_table"                                                        
WHERE; Array 

With XDebug, I placed the exploding query at https://github.com/discoverygarden/embargoes/blob/1.x/src/EmbargoesEmbargoesService.php#L277, i.e. trying to do a node query with an empty orConditionGroup.