Merge pull request #50166 from DirectXMan12/bug/fix-aggregator-with-no-openapi

Automatic merge from submit-queue (batch tested with PRs 49524, 46760, 50206, 50166, 49603)

Handle missing OpenAPI specs on aggregated servers

Previously, the aggregator would fail to actually set up the aggregator
proxy for an API server that was missing an OpenAPI spec.  It would show
up in discovery, but the actual proxying would fail to occur.

Now, we simply log an error if we can't fetch an OpenAPI spec for a
particular aggregated server, and continue on.

Fixes #50165

```release-note
NONE
```

staging/src/k8s.io/kube-aggregator/pkg/apiserver/apiserver.go

@@ -17,6 +17,7 @@ limitations under the License.
 package apiserver
 
 import (
+	"fmt"
 	"net/http"
 	"time"
 
@@ -26,6 +27,7 @@ import (
 	"k8s.io/apimachinery/pkg/runtime"
 	"k8s.io/apimachinery/pkg/runtime/schema"
 	"k8s.io/apimachinery/pkg/runtime/serializer"
+	utilruntime "k8s.io/apimachinery/pkg/util/runtime"
 	"k8s.io/apimachinery/pkg/util/sets"
 	genericapirequest "k8s.io/apiserver/pkg/endpoints/request"
 	"k8s.io/apiserver/pkg/registry/rest"
@@ -261,7 +263,7 @@ func (s *APIAggregator) AddAPIService(apiService *apiregistration.APIService) er
 	}
 	proxyHandler.updateAPIService(apiService)
 	if err := s.openAPIAggregator.loadApiServiceSpec(proxyHandler, apiService); err != nil {
-		return err
+		utilruntime.HandleError(fmt.Errorf("unable to load OpenAPI spec for API service %s: %v", apiService.Name, err))
 	}
 	s.proxyHandlers[apiService.Name] = proxyHandler
 	s.GenericAPIServer.Handler.NonGoRestfulMux.Handle(proxyPath, proxyHandler)