Fixed segfault in VectorUnaryOperationsTest

// - GPU may have different precision than CPU, so exact comparison with

//   the result from host is not possible

template< typename Left, typename Right >

void expect_vectors_near( const Left& v1, const Right& v2 )

void expect_vectors_near( const Left& _v1, const Right& _v2 )

{

   ASSERT_EQ( v1.getSize(), v2.getSize() );

   ASSERT_EQ( _v1.getSize(), _v2.getSize() );

   using LeftNonConstReal = std::remove_const_t< typename Left::RealType >;

   using RightNonConstReal = std::remove_const_t< typename Right::RealType >;

   using LeftVector = Vector< LeftNonConstReal, typename Left::DeviceType, typename Left::IndexType >;

   using RightVector = Vector< RightNonConstReal, typename Right::DeviceType, typename Right::IndexType >;

   using LeftHostVector = Vector< LeftNonConstReal, Devices::Host, typename Left::IndexType >;

   using RightHostVector = Vector< RightNonConstReal, Devices::Host, typename Right::IndexType >;

   // first evaluate expressions

   LeftVector v1; v1 = _v1;

   RightVector v2; v2 = _v2;

   // then copy to host

   LeftHostVector v1_h; v1_h = v1;

   RightHostVector v2_h; v2_h = v1;

   for( int i = 0; i < v1.getSize(); i++ )