--vec terminates execution when passed input with zero length dimension

[philipportner]

TBD

error msg:

terminate called after throwing an instance of 'std::out_of_range'
  what():  invalid arguments '0, 1' passed to dense matrix constructor: it must hold 0 <= rowLowerIncl <= rowUpperExcl <= #rows and rowLowerIncl < #rows (unless both are zero) where #rows of src is '0'