Don't throw if IDispatch.GetTypeInfoCount returns an error HRESULT and 0 as count

Author: elinor-fung

src/libraries/Microsoft.CSharp/src/Microsoft/CSharp/RuntimeBinder/ComInterop/ComRuntimeHelpers.cs

@@ -103,25 +103,29 @@ internal static string GetNameOfType(ComTypes.ITypeInfo typeInfo)
         }
 
         /// <summary>
-        /// Look for typeinfo using IDispatch.GetTypeInfo
+        /// Look for type info using IDispatch.GetTypeInfo
         /// </summary>
         /// <param name="dispatch">IDispatch object</param>
         /// <remarks>
-        /// Some COM objects just dont expose typeinfo. In these cases, this method will return null.
-        /// Some COM objects do intend to expose typeinfo, but may not be able to do so if the type-library is not properly
-        /// registered. This will be considered as acceptable or as an error condition depending on throwIfMissingExpectedTypeInfo
+        /// Some COM objects just don't expose type info. In these cases, this method will return null.
+        /// Some COM objects do intend to expose type info, but may not be able to do so if the type library
+        /// is not properly registered. This will be considered an error.
         /// </remarks>
         /// <returns>Type info</returns>
         internal static ComTypes.ITypeInfo GetITypeInfoFromIDispatch(IDispatch dispatch)
         {
             int hresult = dispatch.TryGetTypeInfoCount(out uint typeCount);
-            Marshal.ThrowExceptionForHR(hresult);
-            Debug.Assert(typeCount <= 1);
             if (typeCount == 0)
             {
+                // COM objects should return a type count of 0 to indicate that type info is not exposed.
+                // Some COM objects may return a non-success HRESULT when type info is not supported, so
+                // we only check the count and not the HRESULT in this case.
                 return null;
             }
 
+            Marshal.ThrowExceptionForHR(hresult);
+            Debug.Assert(typeCount == 1);
+
             IntPtr typeInfoPtr;
             hresult = dispatch.TryGetTypeInfo(0, 0, out typeInfoPtr);
             if (!ComHresults.IsSuccess(hresult))