Check if voice is set before accessing property

Author: valzargaming

src/Discord/Discord.php

@@ -673,7 +673,7 @@ protected function handleVoiceStateUpdate(object $data): void
         $voiceStateUpdate = $this->factory->part(VoiceStateUpdate::class, (array) $data->d, true);
 
         $this->logger->debug('voice state update received', ['guild' => $voiceStateUpdate->guild_id, 'data' => $voiceStateUpdate]);
-        if (isset($this->voice->clients[$voiceStateUpdate->guild_id])) {
+        if (isset($this->voice, $this->voice->clients[$voiceStateUpdate->guild_id])) {
             /** @var VoiceClient */
             $client = $this->voice->clients[$voiceStateUpdate->guild_id];
             $client->handleVoiceStateUpdate($voiceStateUpdate);