eros: don't use WeakReferenceQueue, use stage list

This should fix an unknown crash on macos

src/main/java/de/bixilon/minosoft/gui/eros/util/JavaFXUtil.kt

@@ -13,7 +13,6 @@
 
 package de.bixilon.minosoft.gui.eros.util
 
-import com.sun.javafx.util.WeakReferenceQueue
 import de.bixilon.kutil.cast.CastUtil.unsafeCast
 import de.bixilon.kutil.concurrent.pool.DefaultThreadPool
 import de.bixilon.kutil.reflection.ReflectionUtil.forceSet
@@ -46,7 +45,7 @@ import kotlin.reflect.jvm.javaField
 
 object JavaFXUtil {
     private const val DEFAULT_STYLE = "resource:minosoft:eros/style.css"
-    private val stages: WeakReferenceQueue<Stage> = WeakReferenceQueue()
+    private val stages = StageList()
     lateinit var JAVA_FX_THREAD: Thread
     lateinit var MINOSOFT_LOGO: Image
     lateinit var HOST_SERVICES: HostServices
@@ -62,8 +61,8 @@ object JavaFXUtil {
 
         ErosProfileManager.selected.theme::theme.observeFX(this) {
             stages.cleanup()
-            for (stage in stages.iterator().unsafeCast<Iterator<Stage?>>()) {
-                stage ?: continue
+            for (stage in stages.iterator()) {
+                stage ?: break
                 stage.scene.stylesheets.clear()
                 stage.scene.stylesheets.add(DEFAULT_STYLE)
                 stage.scene.stylesheets.add(getThemeURL(it))

src/main/java/de/bixilon/minosoft/gui/eros/util/StageList.kt

@@ -0,0 +1,68 @@
+/*
+ * Minosoft
+ * Copyright (C) 2020-2023 Moritz Zwerger
+ *
+ * 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, either version 3 of the License, or (at your option) any later version.
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License along with this program. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * This software is not affiliated with Mojang AB, the original developer of Minecraft.
+ */
+
+package de.bixilon.minosoft.gui.eros.util
+
+import de.bixilon.kutil.concurrent.lock.simple.SimpleLock
+import javafx.stage.Stage
+import java.lang.ref.WeakReference
+
+class StageList : Iterable<Stage?> {
+    private val stages: MutableList<WeakReference<Stage>> = mutableListOf()
+    val lock = SimpleLock()
+
+    private fun <T> MutableList<WeakReference<T>>.cleanup() {
+        val iterator = this.iterator()
+        for (reference in iterator) {
+            if (reference.get() != null) {
+                continue
+            }
+            iterator.remove()
+        }
+    }
+
+
+    fun cleanup() {
+        lock.lock()
+        stages.cleanup()
+        lock.unlock()
+    }
+
+    fun add(stage: Stage) {
+        lock.lock()
+        stages += WeakReference(stage)
+        lock.unlock()
+    }
+
+    override fun iterator(): Iterator<Stage?> {
+        return object : Iterator<Stage?> {
+            private val iterator = stages.iterator()
+
+            override fun hasNext(): Boolean {
+                return iterator.hasNext()
+            }
+
+            override fun next(): Stage? {
+                while (iterator.hasNext()) {
+                    val entry = iterator.next().get()
+                    if (entry != null) {
+                        return entry
+                    }
+                    iterator.remove()
+                }
+                return null
+            }
+
+        }
+    }
+}