Make requested changes and utilise AssertionError

Signed-off-by: TheKodeToad <TheKodeToad@proton.me>

libraries/launcher/org/prismlauncher/utils/StringUtils.java

@@ -1,49 +0,0 @@
-// SPDX-License-Identifier: GPL-3.0-only
-/*
- *  Prism Launcher - Minecraft Launcher
- *  Copyright (C) 2022 solonovamax <solonovamax@12oclockpoint.com>
- *
- *  This program is free software: you can redistribute it and/or modify
- *  it under the terms of the GNU General Public License as published by
- *  the Free Software Foundation, version 3.
- *
- *  This program is distributed in the hope that it will be useful,
- *  but WITHOUT ANY WARRANTY; without even the implied warranty of
- *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- *  GNU General Public License for more details.
- *
- *  Linking this library statically or dynamically with other modules is
- *  making a combined work based on this library. Thus, the terms and
- *  conditions of the GNU General Public License cover the whole
- *  combination.
- *
- *  As a special exception, the copyright holders of this library give
- *  you permission to link this library with independent modules to
- *  produce an executable, regardless of the license terms of these
- *  independent modules, and to copy and distribute the resulting
- *  executable under terms of your choice, provided that you also meet,
- *  for each linked independent module, the terms and conditions of the
- *  license of that module. An independent module is a module which is
- *  not derived from or based on this library. If you modify this
- *  library, you may extend this exception to your version of the
- *  library, but you are not obliged to do so. If you do not wish to do
- *  so, delete this exception statement from your version.
- *
- *  You should have received a copy of the GNU General Public License
- *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
- */
-
-package org.prismlauncher.utils;
-
-public final class StringUtils {
-
-    public static String[] splitStringPair(char splitChar, String str) {
-        int splitPoint = str.indexOf(splitChar);
-
-        if (splitPoint == -1)
-            return null;
-
-        return new String[] { str.substring(0, splitPoint), str.substring(splitPoint + 1) };
-    }
-
-}