Fix panic in service invocation when connection fails (#6490)

Fixes error reported by user on Discord: https://discord.com/channels/778680217417809931/1055270900125138975/1109309802435321896Signed-off-by: NItalyPaleAle <43508+ItalyPaleAle@users.noreply.github.com>

pkg/messaging/direct_messaging.go

@@ -267,10 +267,6 @@ func (d *directMessaging) isHTTPEndpoint(appID string) bool {
 	return ok
 }
 
-func noopTeardown(destroy bool) {
-	// Nop
-}
-
 func (d *directMessaging) invokeHTTPEndpoint(ctx context.Context, appID, appNamespace, appAddress string, req *invokev1.InvokeMethodRequest) (*invokev1.InvokeMethodResponse, func(destroy bool), error) {
 	ctx = d.setContextSpan(ctx)
 
@@ -284,13 +280,16 @@ func (d *directMessaging) invokeHTTPEndpoint(ctx context.Context, appID, appName
 		diag.DefaultMonitoring.ServiceInvocationResponseReceived(appID, req.Message().Method, imr.Status().Code, start)
 	}
 
-	return imr, noopTeardown, err
+	return imr, nopTeardown, err
 }
 
 func (d *directMessaging) invokeRemote(ctx context.Context, appID, appNamespace, appAddress string, req *invokev1.InvokeMethodRequest) (*invokev1.InvokeMethodResponse, func(destroy bool), error) {
 	conn, teardown, err := d.connectionCreatorFn(context.TODO(), appAddress, appID, appNamespace)
 	if err != nil {
-		return nil, nil, err
+		if teardown == nil {
+			teardown = nopTeardown
+		}
+		return nil, teardown, err
 	}
 
 	ctx = d.setContextSpan(ctx)