per feedback

Author: twsouthwick

src/DocumentFormat.OpenXml.Framework/EnumerableExtensions.cs

@@ -12,7 +12,7 @@ internal static class EnumerableExtensions
     /// <summary>
     /// Similar to <see cref="Enumerable.FirstOrDefault{TSource}(IEnumerable{TSource})"/> but will also verify that at most there is one.
     /// </summary>
-    public static T? FirstOrDefaultAndMaxOne<T>(this IEnumerable<T> enumerable, Func<Exception>? exThrow = null)
+    public static T? FirstOrDefaultAndMaxOne<T>(this IEnumerable<T> enumerable, Func<Exception>? exceptionFactory = null)
     {
         using var e = enumerable.GetEnumerator();
 
@@ -22,7 +22,7 @@ internal static class EnumerableExtensions
 
             if (e.MoveNext())
             {
-                throw exThrow?.Invoke() ?? throw new InvalidOperationException("Max of a single item should be in the enumerable");
+                throw exceptionFactory?.Invoke() ?? throw new InvalidOperationException(ExceptionMessages.FirstOrDefaultMaxOne);
             }
 
             return first;

src/DocumentFormat.OpenXml.Framework/Resources/ExceptionMessages.Designer.cs

@@ -411,4 +411,7 @@
   <data name="FailedToOpenPackage" xml:space="preserve">
     <value>Package could not be opened for stream. See inner exception for details and be aware that there are behavior differences in stream support between .NET Framework and Core.</value>
   </data>
+  <data name="FirstOrDefaultMaxOne" xml:space="preserve">
+    <value>The enumerable contained more than a single element when only zero or one are allowed.</value>
+  </data>
 </root>