title: .NET Core WebAPI VueJS template publish issue
body: <p>I'm trying out the "VueJS with Asp.Net Core 3.1 Web API Template" found <a href="https://marketplace.visualstudio.com/items?itemName=alexandredotnet.netcorevuejs" rel="nofollow noreferrer">here</a> and it works quite smooth during development. However, I've wanted to see how it handles publishing and I can't manage to get it working.</p>
  
  <p>When running publish to folder, it doesn't move the clientapp/dist folder to the output directory, which is OK, so I thought I'd do it manually. So I've tried moving the contents of the dist folder to output directory with the following paths:</p>
  
  <ul>
  <li>"/publish/clientapp/dist" </li>
  <li>"/publish/dist" </li>
  <li>"/publish/clientapp"</li>
  </ul>
  
  <p>But none of the above seems to work, I get the following error when running the .dll file:</p>
  
  <pre><code>fail: Microsoft.AspNetCore.Server.Kestrel[13]
        Connection id "0HLTD93CRG52F", Request id "0HLTD93CRG52F:00000001": An unhandled exception was thrown by the application.
  System.InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request.
  Your application is running in Production mode, so make sure it has been published, or that you have built your SPA manually. Alternatively you may wish to switch to the Development environment.
  
     at Microsoft.AspNetCore.SpaServices.SpaDefaultPageMiddleware.&lt;&gt;c__DisplayClass0_0.&lt;Attach&gt;b__1(HttpContext context, Func`1 next)
     at Microsoft.AspNetCore.Builder.UseExtensions.&lt;&gt;c__DisplayClass0_1.&lt;Use&gt;b__1(HttpContext context)
     at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.TryServeStaticFile(HttpContext context, String contentType, PathString subPath)
     at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
     at Microsoft.AspNetCore.Builder.UseExtensions.&lt;&gt;c__DisplayClass0_2.&lt;Use&gt;b__2()
     at Microsoft.AspNetCore.SpaServices.SpaDefaultPageMiddleware.&lt;&gt;c__DisplayClass0_0.&lt;Attach&gt;b__0(HttpContext context, Func`1 next)
     at Microsoft.AspNetCore.Builder.UseExtensions.&lt;&gt;c__DisplayClass0_1.&lt;Use&gt;b__1(HttpContext context)
     at Microsoft.AspNetCore.Routing.EndpointMiddleware.Invoke(HttpContext httpContext)
     at Microsoft.AspNetCore.Authorization.AuthorizationMiddleware.Invoke(HttpContext context)
     at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)
  </code></pre>
  
  <p>This is my "UseSpa" in Startup.cs:</p>
  
  <pre><code>app.UseSpa(spa =&gt;
          {
              if (env.IsDevelopment())
                  spa.Options.SourcePath = "ClientApp";
              else
                  spa.Options.SourcePath = "clientapp/dist";
  
              if (env.IsDevelopment())
              {
                  spa.UseVueCli(npmScript: "serve");
              }
  
          });
  </code></pre>
  
  <p>With the above code, I would assume my dist folder should be located in /publish/clientapp/dist, which I've tried, but even then, I get the error mentioned above.</p>
  
  <p>I hope someone can point me in the right direction - thanks in advance :)</p>