BUG: avoid undefined behavior (dereferencing nullptr). Closes #1358
BUG: avoid undefined behavior (dereferencing nullptr). Closes #1358

vfonov/ITK,LucasGandel/ITK,hjmjohnson/ITK,vfonov/ITK,LucasGandel/ITK,vfonov/ITK,thewtex/ITK,vfonov/ITK,BRAINSia/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,LucasGandel/ITK,thewtex/ITK,hjmjohnson/ITK,BRAINSia/ITK,vfonov/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,vfonov/ITK,thewtex/ITK,BRAINSia/ITK,Kitware/ITK,LucasGandel/ITK,thewtex/ITK,Kitware/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,richardbeare/ITK,richardbeare/ITK,richardbeare/ITK,malaterre/ITK,hjmjohnson/ITK,hjmjohnson/ITK,malaterre/ITK,hjmjohnson/ITK,malaterre/ITK,LucasGandel/ITK,richardbeare/ITK,BRAINSia/ITK,Kitware/ITK,Kitware/ITK,thewtex/ITK,BRAINSia/ITK,LucasGandel/ITK,malaterre/ITK,hjmjohnson/ITK,richardbeare/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,LucasGandel/ITK,vfonov/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,LucasGandel/ITK,richardbeare/ITK,hjmjohnson/ITK,Kitware/ITK,BRAINSia/ITK,richardbeare/ITK,vfonov/ITK,Kitware/ITK,malaterre/ITK