Applied fix from trunk for revision: 1609406 
===

Fixed bug reported by Christian Carlow in OFBIZ-5599: Facility Pick Stock Moves "Cannot compare: r-value is null" error when ProductFacilityLocation.minimumStock is not set.



git-svn-id: https://svn.apache.org/repos/asf/ofbiz/branches/release13.07@1609407 13f79535-47bb-0310-9956-ffa450edef68