Fixed a crasher during external cell value query.
Fixed a crasher during external cell value query.

pFmt is sometimes NULL.  We need to check that.

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