Make sure mappingInfo is not null when passed to typedefs, methoddefs, properties and events.

ICSharpCode.Decompiler/CSharp/RequiredNamespaceCollector.cs

@@ -55,10 +55,10 @@ namespace ICSharpCode.Decompiler.CSharp
 		{
 			if (entity == null || entity.MetadataToken.IsNil)
 				return;
-			switch (entity) {
-				case ITypeDefinition td:
 			if (mappingInfo == null)
 				mappingInfo = CSharpDecompiler.GetCodeMappingInfo(entity.ParentModule.PEFile, entity.MetadataToken);
+			switch (entity) {
+				case ITypeDefinition td:
 					namespaces.Add(td.Namespace);
 					HandleAttributes(td.GetAttributes());
 					HandleTypeParameters(td.TypeParameters);
@@ -100,9 +100,6 @@ namespace ICSharpCode.Decompiler.CSharp
 						CollectNamespacesForTypeReference(param.Type);
 					}
 					HandleTypeParameters(method.TypeParameters);
-					if (!method.MetadataToken.IsNil) {
-						if (mappingInfo == null)
-							mappingInfo = CSharpDecompiler.GetCodeMappingInfo(entity.ParentModule.PEFile, entity.MetadataToken);
 					var reader = module.PEFile.Reader;
 					var parts = mappingInfo.GetMethodParts((MethodDefinitionHandle)method.MetadataToken).ToList();
 					foreach (var part in parts) {
@@ -118,7 +115,6 @@ namespace ICSharpCode.Decompiler.CSharp
 							CollectNamespacesFromMethodBody(body, module);
 						}
 					}
-					}
 					break;
 				case IProperty property:
 					HandleAttributes(property.GetAttributes());

ILSpy/LoadedAssembly.cs

@@ -156,7 +156,8 @@ namespace ICSharpCode.ILSpy
 			// runs on background thread
 			if (state is Stream stream) {
 				// Read the module from a precrafted stream
-				module = new PEFile(fileName, stream, stream is MemoryStream ? PEStreamOptions.PrefetchEntireImage : PEStreamOptions.Default, metadataOptions: options);
+				var streamOptions = stream is MemoryStream ? PEStreamOptions.PrefetchEntireImage : PEStreamOptions.Default;
+				module = new PEFile(fileName, stream, streamOptions, metadataOptions: options);
 			} else {
 				// Read the module from disk (by default)
 				stream = new FileStream(fileName, FileMode.Open, FileAccess.Read);