fix crash during file format detection, related #i101863#
fix crash during file format detection, related #i101863#

Change-Id: I2aec2e95f49ab70a9e94c5d52f70855f4381a24e

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