Fixes another possible crash with atcommand time (#5962)

Fixes #5956

Adds a timer data validation check for atcommand time.
Thanks @cahya1992

src/map/atcommand.cpp

@@ -4924,29 +4924,31 @@ ACMD_FUNC(servertime)
 	else {
 		const struct TimerData * timer_data2;
 		if (night_flag == 0) {
-			timer_data = get_timer(night_timer_tid);
-			timer_data2 = get_timer(day_timer_tid);
-			sprintf(temp, msg_txt(sd,235), txt_time(DIFF_TICK(timer_data->tick,gettick())/1000)); // Game time: The game is in daylight for %s.
-			clif_displaymessage(fd, temp);
-			if (DIFF_TICK(timer_data->tick, timer_data2->tick) > 0)
-				sprintf(temp, msg_txt(sd,237), txt_time(DIFF_TICK(timer_data->interval,DIFF_TICK(timer_data->tick,timer_data2->tick)) / 1000)); // Game time: After, the game will be in night for %s.
-			else
-				sprintf(temp, msg_txt(sd,237), txt_time(DIFF_TICK(timer_data2->tick,timer_data->tick)/1000)); // Game time: After, the game will be in night for %s.
-			clif_displaymessage(fd, temp);
-			sprintf(temp, msg_txt(sd,238), txt_time(timer_data->interval / 1000)); // Game time: A day cycle has a normal duration of %s.
-			clif_displaymessage(fd, temp);
+			if ((timer_data = get_timer(night_timer_tid)) != nullptr && (timer_data2 = get_timer(day_timer_tid)) != nullptr) {
+				sprintf(temp, msg_txt(sd,235), txt_time(DIFF_TICK(timer_data->tick,gettick())/1000)); // Game time: The game is in daylight for %s.
+				clif_displaymessage(fd, temp);
+				if (DIFF_TICK(timer_data->tick, timer_data2->tick) > 0)
+					sprintf(temp, msg_txt(sd,237), txt_time(DIFF_TICK(timer_data->interval,DIFF_TICK(timer_data->tick,timer_data2->tick)) / 1000)); // Game time: After, the game will be in night for %s.
+				else
+					sprintf(temp, msg_txt(sd,237), txt_time(DIFF_TICK(timer_data2->tick,timer_data->tick)/1000)); // Game time: After, the game will be in night for %s.
+				clif_displaymessage(fd, temp);
+				sprintf(temp, msg_txt(sd,238), txt_time(timer_data->interval / 1000)); // Game time: A day cycle has a normal duration of %s.
+				clif_displaymessage(fd, temp);
+			} else
+				clif_displaymessage(fd, msg_txt(sd, 231)); // Game time: The game is in permanent daylight.
 		} else {
-			timer_data = get_timer(day_timer_tid);
-			timer_data2 = get_timer(night_timer_tid);
-			sprintf(temp, msg_txt(sd,233), txt_time(DIFF_TICK(timer_data->tick,gettick()) / 1000)); // Game time: The game is in night for %s.
-			clif_displaymessage(fd, temp);
-			if (DIFF_TICK(timer_data->tick,timer_data2->tick) > 0)
-				sprintf(temp, msg_txt(sd,239), txt_time((timer_data->interval - DIFF_TICK(timer_data->tick, timer_data2->tick)) / 1000)); // Game time: After, the game will be in daylight for %s.
-			else
-				sprintf(temp, msg_txt(sd,239), txt_time(DIFF_TICK(timer_data2->tick, timer_data->tick) / 1000)); // Game time: After, the game will be in daylight for %s.
-			clif_displaymessage(fd, temp);
-			sprintf(temp, msg_txt(sd,238), txt_time(timer_data->interval / 1000)); // Game time: A day cycle has a normal duration of %s.
-			clif_displaymessage(fd, temp);
+			if ((timer_data = get_timer(day_timer_tid)) != nullptr && (timer_data2 = get_timer(night_timer_tid)) != nullptr) {
+				sprintf(temp, msg_txt(sd,233), txt_time(DIFF_TICK(timer_data->tick,gettick()) / 1000)); // Game time: The game is in night for %s.
+				clif_displaymessage(fd, temp);
+				if (DIFF_TICK(timer_data->tick,timer_data2->tick) > 0)
+					sprintf(temp, msg_txt(sd,239), txt_time((timer_data->interval - DIFF_TICK(timer_data->tick, timer_data2->tick)) / 1000)); // Game time: After, the game will be in daylight for %s.
+				else
+					sprintf(temp, msg_txt(sd,239), txt_time(DIFF_TICK(timer_data2->tick, timer_data->tick) / 1000)); // Game time: After, the game will be in daylight for %s.
+				clif_displaymessage(fd, temp);
+				sprintf(temp, msg_txt(sd,238), txt_time(timer_data->interval / 1000)); // Game time: A day cycle has a normal duration of %s.
+				clif_displaymessage(fd, temp);
+			} else
+				clif_displaymessage(fd, msg_txt(sd,232)); // Game time: The game is in permanent night.
 		}
 	}