fix: address comment on checking configs

Author: hhieuu

plugins/otel/main.go

@@ -170,6 +170,9 @@ func (p *OtelPlugin) HTTPTransportStreamChunkHook(ctx *schemas.BifrostContext, r
 
 // ValidateConfig validates values of PluginConfig and set up defaults where needed.
 func ValidateConfig(config *Config) (*Config, error) {
+	if config == nil {
+		return nil, fmt.Errorf("config is required")
+	}
 	// Validating fields
 	if config.ServiceName == "" {
 		config.ServiceName = "bifrost"

plugins/otel/metrics.go

@@ -78,7 +78,7 @@ func initOTELMeterProvider(ctx context.Context, serviceName string, config *Conf
 	case ProtocolGRPC:
 		exporter, exporterErr = initOTELGRPCExporter(ctx, config)
 	default:
-		exporterErr = errors.New(fmt.Sprintf("invalid protocol '%s'", string(config.MetricsProtocol)))
+		exporterErr = fmt.Errorf("invalid protocol '%s'", string(config.MetricsProtocol))
 	}
 	if exporterErr != nil {
 		return nil, errors.Wrap(exporterErr, "fail to init OTEL metrics exporter")