reformulate message

Sim/Simulation/DepthprobeSimulation.cpp

@@ -90,7 +90,7 @@ void DepthprobeSimulation::runComputation(const ReSample& re_sample, size_t i, d
 {
     if (m_scan->wavelengthDistribution() || m_scan->alphaDistribution())
         throw std::runtime_error(
-            "Depthprobe simulation does not support alpha and lambda distributions.");
+            "Depthprobe simulation supports neither alpha nor lambda distributions.");
 
     const size_t n_z = m_z_axis->size();
     std::valarray<double> intensities; //!< simulated intensity for given z positions

Sim/Simulation/OffspecSimulation.cpp

@@ -84,7 +84,7 @@ void OffspecSimulation::runComputation(const ReSample& re_sample, size_t i, doub
     if (auto phys_scan = dynamic_cast<PhysicalScan*>(m_scan.get()))
         if (phys_scan->wavelengthDistribution() || phys_scan->alphaDistribution())
             throw std::runtime_error(
-                "Offspecular simulation does not support alpha and lambda distributions.");
+                "Offspecular simulation supports neither alpha nor lambda distributions.");
 
     if (m_cache.empty())
         m_cache.resize(nElements(), 0.0);