impl member join and leave logs

src/main/java/cc/fascinated/bat/features/logging/LogProfile.java

@@ -37,6 +37,9 @@ public class LogProfile extends Serializable {
      */
     public TextChannel getLogChannel(LogType logType) {
         TextChannel textChannel = this.logChannels.get(logType);
+        if (textChannel == null) {
+            return null;
+        }
         // Ensure the channel exists
         if (DiscordService.JDA.getTextChannelById(textChannel.getId()) == null) {
             this.logChannels.remove(logType);