SP-1175 -- Backport of BISERVER-11105 - Migrator: MondrianCatalogHelper NullPointerException on Import (5.0)

What was done:
1)Added check if process could be continued and continue it.
Merge pull request #1498 from kolinus/SP-1175

Sp 1175 -- Backport of BISERVER-11105 - Migrator: MondrianCatalogHelper NullPointerException on Import (5.0)