command/{Queue,Other}: eliminate local "bool" variable

src/command/OtherCommands.cxx

@@ -308,8 +308,6 @@ CommandResult
 handle_setvol(Client &client, ConstBuffer<const char *> args)
 {
 	unsigned level;
-	bool success;
-
 	if (!check_unsigned(client, &level, args.front()))
 		return CommandResult::ERROR;
 
@@ -318,8 +316,7 @@ handle_setvol(Client &client, ConstBuffer<const char *> args)
 		return CommandResult::ERROR;
 	}
 
-	success = volume_level_change(client.partition.outputs, level);
-	if (!success) {
+	if (!volume_level_change(client.partition.outputs, level)) {
 		command_error(client, ACK_ERROR_SYSTEM,
 			      "problems setting volume");
 		return CommandResult::ERROR;

src/command/QueueCommands.cxx

@@ -249,13 +249,11 @@ CommandResult
 handle_playlistinfo(Client &client, ConstBuffer<const char *> args)
 {
 	unsigned start = 0, end = std::numeric_limits<unsigned>::max();
-	bool ret;
 
 	if (args.size == 1 && !check_range(client, &start, &end, args.front()))
 		return CommandResult::ERROR;
 
-	ret = playlist_print_info(client, client.playlist, start, end);
-	if (!ret)
+	if (!playlist_print_info(client, client.playlist, start, end))
 		return print_playlist_result(client,
 					     PlaylistResult::BAD_RANGE);
 

src/command/StickerCommands.cxx

@@ -166,17 +166,15 @@ handle_sticker_song(Client &client, ConstBuffer<const char *> args)
 			}
 		}
 
-		bool success;
 		struct sticker_song_find_data data = {
 			client,
 			args[3],
 		};
 
-		success = sticker_song_find(*db, base_uri, data.name,
-					    op, value,
-					    sticker_song_find_print_cb, &data,
-					    error);
-		if (!success) {
+		if (!sticker_song_find(*db, base_uri, data.name,
+				       op, value,
+				       sticker_song_find_print_cb, &data,
+				       error)) {
 			if (error.IsDefined())
 				return print_error(client, error);