Do not crash when provider segment doesnt exist

Return error result when provider segment doesn't exist when reading
laser scanner features.

source/armarx/navigation/memory/client/laser_scanner_features/Reader.cpp

@@ -194,6 +194,16 @@ namespace armarx::navigation::memory::client::laser_scanner_features
                     .errorMessage = qResult.errorMessage};
         }
 
+        const auto coreSegment = qResult.memory.getCoreSegment(properties.coreSegmentName);
+        if (not coreSegment.hasProviderSegment(query.providerName))
+        {
+            ARMARX_VERBOSE << "Provider segment `" << query.providerName
+                           << "` does not exist (yet).";
+            return {.features = {},
+                    .status = Result::Status::Error,
+                    .errorMessage = "Provider segment " + query.providerName + " does not exist"};
+        }
+
         // now create result from memory
         const armem::wm::ProviderSegment& providerSegment =
             qResult.memory.getCoreSegment(properties.coreSegmentName)