Fix Coverity Scan warnings

Author: rouault

apps/gdalalg_raster_neighbors.cpp

@@ -451,7 +451,8 @@ bool GDALRasterNeighborsAlgorithm::RunStep(GDALPipelineStepRunContext &)
             def.size = m_size;
             const double dfWeight =
                 m_method[i] == "mean"
-                    ? 1.0 / (static_cast<double>(m_size) * m_size)
+                    ? 1.0 / (static_cast<double>(m_size) * m_size +
+                             std::numeric_limits<double>::min())
                     : 1.0;
             def.adfCoefficients.resize(static_cast<size_t>(m_size) * m_size,
                                        dfWeight);

gcore/gdalalgorithm.cpp

@@ -4611,7 +4611,7 @@ void GDALAlgorithm::SetAutoCompleteFunctionForFieldName(
                                           GDAL_OF_VECTOR | GDAL_OF_READONLY));
                     if (poDS)
                     {
-                        const auto layerName = layerNameArg.Get<std::string>();
+                        const auto &layerName = layerNameArg.Get<std::string>();
                         if (layerName.empty())
                         {
                             // Loop through all layers