Emscripten: Immediately mark presentable if no url is specified

Also log failed requests.

src/PowderToy.cpp

@@ -496,6 +496,10 @@ int Main(int argc, char *argv[])
 				Platform::MarkPresentable();
 			}
 		}
+		else
+		{
+			Platform::MarkPresentable();
+		}
 
 		MainLoop();
 	};

src/client/http/Request.cpp

@@ -146,6 +146,10 @@ namespace http
 		{
 			std::cerr << *error << std::endl;
 		}
+		else if (statusCode >= 400)
+		{
+			std::cerr << "status code " << statusCode << " for request to " << uri << std::endl;
+		}
 	}
 
 	const char *StatusText(int ret)