Check pointer to avoid crash
Check pointer to avoid crash

rdebroiz/medInria-public,aabadie/medInria-public,rdebroiz/medInria-public,NicolasSchnitzler/medInria-public,aabadie/medInria-public,rdebroiz/medInria-public,aabadie/medInria-public,NicolasSchnitzler/medInria-public,NicolasSchnitzler/medInria-public