feat: Validation should happen before first steps in deploy

The validation if the configs are valid happened after the deployment-graph was build, and the caches were preloaded. This does not make sense, so this change moves the validation up.

pkg/deploy/deploy.go

@@ -73,9 +73,6 @@ func Deploy(ctx context.Context, projects []project.Project, environmentClients
 		log.Info("%s set, limiting concurrent deployments to %d", environment.ConcurrentDeploymentsEnvKey, maxConcurrentDeployments)
 		concurrentDeploymentsLimiter = rest.NewConcurrentRequestLimiter(maxConcurrentDeployments)
 	}
-
-	preloadCaches(ctx, projects, environmentClients)
-	g := graph.New(projects, environmentClients.Names())
 	deploymentErrors := make(deployErrors.EnvironmentDeploymentErrors)
 
 	// note: Currently the validation works 'environment-independent', but that might be something we should reconsider to improve error messages
@@ -86,6 +83,9 @@ func Deploy(ctx context.Context, projects []project.Project, environmentClients
 		errors.As(validationErrs, &deploymentErrors)
 	}
 
+	preloadCaches(ctx, projects, environmentClients)
+	g := graph.New(projects, environmentClients.Names())
+
 	for env, clientset := range environmentClients {
 		ctx := newContextWithEnvironment(ctx, env)
 		log.WithCtxFields(ctx).Info("Deploying configurations to environment %q...", env.Name)