message: Adds duplication functions for single units or courses
diff: @@ -148,7 +148,7 @@ courseSchema.statics.import = function (course: ICourse, admin: IUser) {
  })
  .catch((err: Error) => {
  const newError = new InternalServerError('Failed to import course');
  - newError.stack += '\nCaused by: ' + err.stack;
  + newError.stack += '\nCaused by: ' + err.message + '\n' + err.stack;
  throw newError;
  });
  };
  