[Fix][kubectl-plugin] ray job submit runtime-env-json null error (ray…

…-project#3063)

Signed-off-by: Chi-Sheng Liu <chishengliu@chishengliu.com>

kubectl-plugin/pkg/cmd/job/job_submit.go

@@ -232,7 +232,7 @@ func (options *SubmitJobOptions) Validate() error {
 		}
 
 		runtimeEnvYaml := options.RayJob.Spec.RuntimeEnvYAML
-		if options.runtimeEnv == "" && options.runtimeEnvJson == "" {
+		if options.runtimeEnv == "" && options.runtimeEnvJson == "" && runtimeEnvYaml != "" {
 			runtimeJson, err := yaml.YAMLToJSON([]byte(runtimeEnvYaml))
 			if err != nil {
 				return fmt.Errorf("Failed to convert runtime env to json: %w", err)