Fix nil panics and route loss during config sync cycles

gateway/router/handler.go

@@ -188,6 +188,10 @@ func (r *Handler) Handle(ctx context.Context, writer http.ResponseWriter, reques
 		http.Error(writer, err.Error(), http.StatusInternalServerError)
 		return
 	}
+	if aComponent == nil {
+		http.Error(writer, "component not available", http.StatusServiceUnavailable)
+		return
+	}
 	aResponse, err := r.safelyHandleComponent(ctx, request, aComponent)
 	if err != nil {
 		r.writeErrorResponse(ctx, writer, aComponent, err, http.StatusBadRequest)
@@ -237,6 +241,20 @@ func (r *Handler) writeErrorResponse(ctx context.Context, w http.ResponseWriter,
 		execCtx.SetError(err)
 	}
 	responseStatus := r.responseStatusError(message, anObjectErr)
+	if aComponent == nil || aComponent.Output.Type.Parameters == nil {
+		errAsBytes, marshalErr := goJson.Marshal(responseStatus)
+		if marshalErr != nil {
+			w.WriteHeader(http.StatusInternalServerError)
+			w.Write([]byte("could not parse error message"))
+			return
+		}
+		if execCtx != nil {
+			execCtx.StatusCode = statusCode
+		}
+		w.WriteHeader(statusCode)
+		w.Write(errAsBytes)
+		return
+	}
 	statusParameter := aComponent.Output.Type.Parameters.LookupByLocation(state.KindOutput, "status")
 	if statusParameter == nil {
 		errAsBytes, marshalErr := goJson.Marshal(responseStatus)

gateway/service.go

@@ -224,6 +224,17 @@ func (r *Service) syncChanges(ctx context.Context, metrics *gmetric.Service, sta
 		return err
 	}
 	r.mux.Lock()
+	newCount := len(mainRouter.paths)
+	oldCount := 0
+	if r.mainRouter != nil {
+		oldCount = len(r.mainRouter.paths)
+	}
+	if newCount < oldCount {
+		r.mux.Unlock()
+		fmt.Printf("[INFO]: routers rebuild skipped (new config has %d routes vs %d existing, keeping existing)\n", newCount, oldCount)
+		return nil
+	}
+	fmt.Printf("[INFO]: router replacing old(%d routes) with new(%d routes)\n", oldCount, newCount)
 	r.mainRouter = mainRouter
 	r.mux.Unlock()
 	fmt.Printf("[INFO]: routers rebuild completed after: %s\n", time.Since(start))

repository/provider.go

@@ -26,7 +26,9 @@ func (p *Provider) Component(ctx context.Context, opts ...Option) (*Component, e
 	p.mux.Lock()
 	defer p.mux.Unlock()
 	if p.control.ChangeKind() == version.ChangeKindDeleted {
-		//TODO maybe return 404 error
+		if p.component != nil {
+			return p.component, nil
+		}
 		return nil, nil
 	}
 	aComponent, err := p.newComponent(ctx, opts...)