Make addArrayReaders a no-op for empty arrays

Author: gsakkis

pdal/PyPipeline.cpp

@@ -69,6 +69,8 @@ void addArrayReaders(PipelineExecutor* executor, std::vector<std::shared_ptr<Arr
 #ifndef _WIN32
     ::dlopen("libpdal_base.so", RTLD_NOLOAD | RTLD_GLOBAL);
 #endif
+    if (arrays.empty())
+        return;
 
     PipelineManager& manager = executor->getManager();
     std::vector<Stage *> roots = manager.roots();