fix server locking with DMs disabled

Author: danthe1st

src/main/java/net/discordjug/javabot/systems/moderation/server_lock/ServerLockManager.java

@@ -201,9 +201,12 @@ private void checkForEndOfRaid(Guild guild) {
 	 * @param event The user who joined.
 	 */
 	private void rejectUserDuringRaid(@NotNull GuildMemberJoinEvent event) {
-		event.getUser().openPrivateChannel().queue(c ->
-				c.sendMessage(Constants.INVITE_URL).setEmbeds(buildServerLockEmbed(event.getGuild())).queue(msg ->
-						event.getMember().kick().queue()));
+		event.getUser().openPrivateChannel().flatMap(c ->
+				c.sendMessage(Constants.INVITE_URL)
+					.setEmbeds(buildServerLockEmbed(event.getGuild())))
+			.queue(msg -> kickMemberForServerlock(event.getGuild(), event.getMember()),
+					//in case of error, still kick the user
+					err -> kickMemberForServerlock(event.getGuild(), event.getMember()));
 		String diff = new TimeUtils().formatDurationToNow(event.getMember().getTimeCreated());
 		notificationService.withGuild(event.getGuild()).sendToModerationLog(c -> c.sendMessageFormat(
 			"**%s** (%s old) tried to join this server.",
@@ -222,17 +225,13 @@ private void rejectUserDuringRaid(@NotNull GuildMemberJoinEvent event) {
 	 */
 	public void lockServer(Guild guild, @NotNull Collection<Member> potentialRaiders, @Nullable User lockedBy) {
 		for (Member member : potentialRaiders) {
-			member.getUser().openPrivateChannel().queue(c -> {
-				c.sendMessage(Constants.INVITE_URL).setEmbeds(buildServerLockEmbed(guild)).queue(msg -> {
-					member.kick().queue(
-							success -> {},
-							error -> notificationService.withGuild(guild).sendToModerationLog(m -> m.sendMessageFormat(
-								"Could not kick member %s%n> `%s`",
-								UserUtils.getUserTag(member.getUser()),
-								error.getMessage()
-							)));
-				});
-			});
+			member.getUser().openPrivateChannel().flatMap(c -> 
+				c.sendMessage(Constants.INVITE_URL).setEmbeds(buildServerLockEmbed(guild))
+			).queue(msg -> 
+				kickMemberForServerlock(guild, member),
+				//if message cannot be sent, still kick them
+				e -> kickMemberForServerlock(guild, member)
+				);
 		}
 
 		String membersString = potentialRaiders.stream()
@@ -264,6 +263,15 @@ public void lockServer(Guild guild, @NotNull Collection<Member> potentialRaiders
 		}
 	}
 
+	private void kickMemberForServerlock(Guild guild, Member member) {
+		member.kick().queue(
+				success -> {},
+				error -> notificationService.withGuild(guild).sendToModerationLog(m -> m.sendMessageFormat(
+					"Could not kick member %s%n> `%s`",
+					UserUtils.getUserTag(member.getUser()),
+					error.getMessage())));
+	}
+
 	/**
 	 * Unlocks the server after it has been deemed that we're no longer in a raid.
 	 *