Fix backtrace not being shown if error_message is ""
Fix backtrace not being shown if error_message is ""

Change-Id: I327e2a79881b7036143877653136b8e2bd7a2f9b

intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre,intel-hpdd/intel-manager-for-lustre