fixing AccessViolationException on ReadMetadataHeader (#24464)

src/ExpressionEvaluator/Core/Source/ExpressionCompiler/DkmUtilities.cs

@@ -49,6 +49,13 @@ private static IEnumerable<DkmClrModuleInstance> GetModulesInAppDomain(this DkmC
             DkmClrAppDomain appDomain, 
             ImmutableArray<MetadataBlock> previousMetadataBlocks)
         {
+            // Add a dummy data item to the appdomain to add it to the disposal queue when the debugged process is shutting down.
+            // This should prevent from attempts to use the Metadata pointer for dead debugged processes.
+            if (appDomain.GetDataItem<AppDomainLifetimeDataItem>() == null)
+            {
+                appDomain.SetDataItem(DkmDataCreationDisposition.CreateNew, new AppDomainLifetimeDataItem());
+            }
+
             var builder = ArrayBuilder<MetadataBlock>.GetInstance();
             IntPtr ptr;
             uint size;
@@ -324,5 +331,7 @@ internal MetadataContextItem(TMetadataContext metadataContext)
                 this.MetadataContext = metadataContext;
             }
         }
+
+        private sealed class AppDomainLifetimeDataItem : DkmDataItem { }
     }
 }