Fixing crash with dereferencing front() and back() of an empty vector
Fixing crash with dereferencing front() and back() of an empty vector

Change-Id: If7204614aa7a650f4a2804fc63dd3301ece2281e

JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core,JurassicWordExcel/core