NullReference in DateMappingDescriptor

[ThomasVer]

When trying to add a field to a date mapping in a DynamicTemplate, I keep getting a NullReference.
See below for a snippet of my code:

.DynamicTemplates(d => d
                        .Add(dt => dt
                            .Name("date_template")
                            .Match("*_date")
                            .MatchMappingType("date")
                            .Mapping(mp => mp
                                .Date(date => date
                                    .Format("basic_date || date|| yyyy/MM/dd || dd/MM/yyyy || dd-MM-yyyy || MM/dd/yyyy || MM-dd-yyyy")
                                    .Fields(f => f
                                        .String(fs => fs
                                            .Name("raw")
                                            .Analyzer("number_delimiter")
                                        )
                                    )
                                )
                            )
                        )

Error is encountered on this line:

[NullReferenceException: Object reference not set to an instance of an object.]
   Nest.DateMappingDescriptor`1.Fields(Func`2 fieldSelector) in c:\Users\gmarz\code\elasticsearch-net\src\Nest\Domain\Mapping\Descriptors\DateMappingDescriptor.cs:87

[Mpdreamz]

ty @ThomasVer using multifield on date properties indeed resulted in a NRE, this should now be fixed.

Thanks for reporting!