Fix up load dependencies to handle circular and multi dependencies

lib/mod_list.dart

@@ -400,13 +400,30 @@ class ModList {
     return bestOrder;
   }
 
+  List<String> loadDependencies(
+    String modId, [
+    List<String>? toEnable,
+    Map<String, bool>? seen,
+  ]) {
+    final mod = mods[modId]!;
+    toEnable ??= <String>[];
+    seen ??= <String, bool>{};
+    for (final dep in mod.dependencies) {
+      final depMod = mods[dep]!;
+      if (seen[dep] == true) {
+        throw Exception('Cyclic dependency detected: $modId -> $dep');
+      }
+      seen[dep] = true;
+      toEnable.add(depMod.id);
+      loadDependencies(depMod.id, toEnable, seen);
+    }
+    return toEnable;
+  }
+
   List<String> loadRequired() {
     final toEnable = <String>[];
     for (final modid in activeMods.keys) {
-      final mod = mods[modid]!;
-      for (final dep in mod.dependencies) {
-        toEnable.add(dep);
-      }
+      loadDependencies(modid, toEnable);
     }
     for (final modid in toEnable) {
       setEnabled(modid, true);