If you have an error (e.g. null object exception) in .NET code that you can't debug locally - for instance if your app is running on a client's server - then write out all relevant details in memory to a file.
Install ObjectDumper using nuget: https://www.nuget.org/packages/ObjectDumper/
ObjectDumper creates extension methods on objects like DumpToString and Dump.
So log the object to examine straight to a file or using log4net:
_logger.Error(result.DumpToString("GetAllPatientConsultationDataForPdf"));
