DataImporter: NullPointer when trying to use a configuration without namingConventions

[PavelBal]

When trying to load data using a configuration without a namingConventions (e.g. creating a configuration in PK-Sim and saving it prior to importing any sheet) from R, a nullpointer is produced:

Error in rClr::clrCall(dataImporterTask, "ImportExcelFromConfiguration",  : 
  Type:    System.NullReferenceException
Message: Object reference not set to an instance of an object.
Method:  System.String NameFromConvention(System.Collections.Generic.IEnumerable`1[OSPSuite.Infrastructure.Import.Core.MetaDataMappingConverter], System.String, System.String, System.String)
Stack trace:
   at OSPSuite.Infrastructure.Import.Core.ParsedDataSet.NameFromConvention(IEnumerable`1 mappings, String convention, String fileName, String sheetName) in D:\Work\OSPS\Repos\OSPSuite.Core\src\OSPSuite.Infrastructure.Import\Core\IParsedDataSet.cs:line 36
   at OSPSuite.Infrastructure.Import.Services.Importer.<>c__DisplayClass8_1.<NamesFromConvention>b__1(ParsedDataSet s) in D:\Work\OSPS\Repos\OSPSuite.Core\src\OSPSuite.Infrastructure.Import\Services\Importer.cs:line 134
   at System.Linq.Enumerable.WhereSelectListIterator`2.MoveNext()
   at System.Linq.Enumerable.<SelectManyIterator>d__17`2.MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)

CompiledDataSet_oneSheet.xlsx
dataImporterConfiguration_noSheets.zip