coverity#704628/704629/704630 Explicit null dereferenced
coverity#704628/704629/704630 Explicit null dereferenced

+ return early if no whichid or after default case

Change-Id: I40f3ec310604ccde22022dd2e82984b0f3057307
Reviewed-on: https://gerrit.libreoffice.org/2869
Reviewed-by: Noel Power <5d8953a81ee7faf03fd3845d9c88b1bd8aadcf4c@suse.com>
Tested-by: Noel Power <5d8953a81ee7faf03fd3845d9c88b1bd8aadcf4c@suse.com>

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