address PR feedback

Signed-off-by: Roman Dmytrenko <[email protected]>

Author: erka

openfeature/multi/multiprovider.go

@@ -220,17 +220,17 @@ func NewProvider(evaluationStrategy EvaluationStrategy, options ...Option) (*Pro
 	}
 
 	if len(config.providers) == 0 {
-		return nil, errors.New("providers cannot be nil or empty")
+		return nil, errors.New("no providers configured: at least one provider must be registered using WithProvider()")
 	}
 
 	providers := make([]NamedProvider, 0, len(config.providers))
 	collectedHooks := make([]of.Hook, 0, len(config.providers))
 	for i, provider := range config.providers {
 		// Validate Providers
 		if provider.FeatureProvider == nil {
-			return nil, fmt.Errorf("provider at %d cannot be nil", i)
+			return nil, fmt.Errorf("provider %s at %d cannot be nil", provider.name, i)
 		}
-		if provider.Name() == "" {
+		if provider.name == "" {
 			return nil, fmt.Errorf("provider name at %d cannot be the empty string", i)
 		}
 
@@ -448,8 +448,13 @@ func (p *Provider) startListening(ctx context.Context, name string, h of.EventHa
 	for {
 		select {
 		case e := <-h.EventChannel():
+			if e.EventMetadata == nil {
+				e.EventMetadata = make(map[string]any)
+			}
 			e.EventMetadata[MetadataProviderName] = name
-			e.EventMetadata[MetadataProviderType] = h.(of.FeatureProvider).Metadata().Name
+			if p, ok := h.(of.FeatureProvider); ok {
+				e.EventMetadata[MetadataProviderType] = p.Metadata().Name
+			}
 			p.inboundEvents <- namedEvent{
 				Event:        e,
 				providerName: name,

openfeature/multi/multiprovider_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"regexp"
 	"testing"
+	"time"
 
 	of "github.com/open-feature/go-sdk/openfeature"
 	imp "github.com/open-feature/go-sdk/openfeature/memprovider"
@@ -342,7 +343,14 @@ func TestMultiProvider_StateUpdateWithSameTypeProviders(t *testing.T) {
 	primaryProvider.EmitEvent(of.ProviderError, "fail to fetch data")
 	secondaryProvider.EmitEvent(of.ProviderReady, "rev 1")
 	// wait for processing
-	<-mp.outboundEvents
+	require.Eventually(t, func() bool {
+		select {
+		case <-mp.outboundEvents:
+			return true
+		default:
+			return false
+		}
+	}, time.Second, 50*time.Millisecond, "expected event was not emitted within timeout")
 
 	// Check the state after the error event
 	mp.providerStatusLock.Lock()
@@ -444,7 +452,14 @@ func TestMultiProvider_Track(t *testing.T) {
 		errorProvider.EmitEvent(of.ProviderError, "error")
 
 		// wait for event processing
-		<-mp.outboundEvents
+		require.Eventually(t, func() bool {
+			select {
+			case <-mp.outboundEvents:
+				return true
+			default:
+				return false
+			}
+		}, time.Second, 50*time.Millisecond, "expected event was not emitted within timeout")
 
 		trackingEventName := "page-view"
 		details := of.TrackingEventDetails{}