Fix empty response handling

Author: SteveSandersonMS

src/Components/Web.JS/dist/Release/blazor.server.js

@@ -118,11 +118,11 @@ export async function performEnhancedPageLoad(internalDestinationHref: string, f
       }
 
       const responseContentType = response.headers.get('content-type');
-      if (responseContentType?.startsWith('text/html')) {
+      if (responseContentType?.startsWith('text/html') && initialContent) {
         // For HTML responses, regardless of the status code, display it
         const parsedHtml = new DOMParser().parseFromString(initialContent, 'text/html');
         synchronizeDomContent(document, parsedHtml);
-      } else if (responseContentType?.startsWith('text/')) {
+      } else if (responseContentType?.startsWith('text/') && initialContent) {
         // For any other text-based content, we'll just display it, because that's what
         // would happen if this was a non-enhanced request.
         replaceDocumentWithPlainText(initialContent);
@@ -248,9 +248,7 @@ function splitStream(frameBoundaryMarker: string) {
       }
     },
     flush(controller) {
-      if (buffer) {
-        controller.enqueue(buffer);
-      }
+      controller.enqueue(buffer);
     }
   });
 }

src/Components/Web.JS/dist/Release/blazor.web.js

@@ -749,7 +749,7 @@ public async Task CanModifyTheHttpResponseDuringEventHandling()
 
     [Theory]
     [InlineData(true)]
-    [InlineData(false, Skip = "https://github.com/dotnet/aspnetcore/issues/49115")]
+    [InlineData(false)]
     public void FormNoAntiforgeryReturnBadRequest(bool suppressEnhancedNavigation)
     {
         var dispatchToForm = new DispatchToForm(this)