BUG: added check on get_dimension in sct_utils
BUG: added check on get_dimension in sct_utils

Former-commit-id: 879cda9efa327c6a6544a0e3a6d7bbea7d6da6f6
Former-commit-id: ab1b8d45ee549268fd6e4d9ad949bf7c98859a12
3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox,3324fr/spinalcordtoolbox