Possible null reference argument for parameter 'ilStream' in 'ManagedPEBuilder.ManagedPEBuilder(PEHeaderBuilder header, MetadataRootBuilder metadataRootBuilder, BlobBuilder ilStream, BlobBuilder? mappedFieldData = null, BlobBuilder? managedResources = null, ResourceSectionBuilder? nativeResources = null, DebugDirectoryBuilder? debugDirectoryBuilder = null, int strongNameSignatureSize = 128, MethodDefinitionHandle entryPoint = default(MethodDefinitionHandle), CorFlags flags = CorFlags.ILOnly, Func<IEnumerable<Blob>, BlobContentId>? deterministicIdProvider = null)'.