Fix EffConnect NPE with no players (#4387)

src/main/java/ch/njol/skript/effects/EffConnect.java

@@ -59,7 +59,8 @@ public class EffConnect extends Effect {
 	@Override
 	protected void execute(Event e) {
 		String server = this.server.getSingle(e);
-		if (server == null)
+		Player[] players = this.players.getArray(e);
+		if (server == null || players.length == 0)
 			return;
 
 		// the message channel is case sensitive so let's fix that
@@ -68,7 +69,7 @@ protected void execute(Event e) {
 				// for loop isn't as pretty a stream, but will be faster with tons of servers
 				for (String validServer : response.readUTF().split(", ")) {
 					if (validServer.equalsIgnoreCase(server)) {
-						for (Player player : players.getArray(e))
+						for (Player player : players)
 							Utils.sendPluginMessage(player, BUNGEE_CHANNEL, CONNECT_CHANNEL, validServer);
 						break;
 					}

src/main/java/ch/njol/skript/util/Utils.java

@@ -412,10 +412,13 @@ public static CompletableFuture<ByteArrayDataInput> sendPluginMessage(Player pla
 	 * @param data the data to add to the outgoing message
 	 * @return a completable future for the message of the responding plugin message, if there is one.
 	 * this completable future will complete exceptionally if the player is null.
+	 * @throws IllegalStateException when there are no players online
 	 */
 	public static CompletableFuture<ByteArrayDataInput> sendPluginMessage(String channel,
-			Predicate<ByteArrayDataInput> messageVerifier, String... data) {
+			Predicate<ByteArrayDataInput> messageVerifier, String... data) throws IllegalStateException {
 		Player firstPlayer = Iterables.getFirst(Bukkit.getOnlinePlayers(), null);
+		if (firstPlayer == null)
+			throw new IllegalStateException("There are no players online");
 		return sendPluginMessage(firstPlayer, channel, messageVerifier, data);
 	}