fixes for avoid network error in client

- return 200 OK for /ContentWebService.asmx
- return 404 (and log error) on connection error to asset provider server

src/Controllers/Common/AnalyticsController.cs

@@ -14,6 +14,7 @@ namespace sodoff.Controllers.Common
         }
 
         [Route("ping")]
+        [Route("ContentWebService.asmx")] // ping URL used by SoD
         public IActionResult Ping()
         {
             return Ok();

src/Middleware/AssetMiddleware.cs

@@ -138,11 +138,12 @@ public class AssetMiddleware
                 }
             }
         }
-        catch (Exception) {
+        catch (Exception err) {
+            Console.WriteLine($"{err}");
             if (File.Exists(filePathTmp))
                 File.Delete(filePathTmp);
             if (!context.Response.HasStarted)
-                context.Response.StatusCode = 502;
+                context.Response.StatusCode = 404;
         }
     }