"Find Unreferenced Assets" has many false positives

[Crystal-Shard]

Describe the bug

The game Valdis Story: Abyssal City can be opened in UndertaleModTool and appears to be fully compatible, except that the Find Unreferenced Assets menu option doesn't work.

With 'strings' deselected, it reports many false positives among unreferenced assets.
With 'strings' selected, a null pointer exception occurs.

Reproducing steps

1. use Find Unreferenced Assets from the menu
2. select every type of asset in the menu, except for string
3. I get a list showing pretty much every asset in the game. Apparently UMT detects every asset as unreferenced.

Alternatively:

1. use Find Unreferenced Assets from the menu
2. select every type of asset in the menu, including string
3. I get the error "Value cannot be null. (Parameter 'source')" and a stack trace, shown below.
4. No results are displayed; EMT does not crash and continues functioning normally.

System.AggregateException: One or more errors occurred. (Value cannot be null. (Parameter 'source')) (Value cannot be null. (Parameter 'source')) (Value cannot be null. (Parameter 'source')) (Value cannot be null. (Parameter 'source'))
 ---> System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c.<.cctor>b__9_42(Object objSrc, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 455
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.GetReferencesOfObject(Object obj, UndertaleData data, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1418
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c__DisplayClass7_0.<GetUnreferencedObjects>b__3(Tuple`2 range) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1532
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
--- End of stack trace from previous location ---
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
   at System.Threading.Tasks.TaskReplicator.Replica.Execute()
   --- End of inner exception stack trace ---
   at System.Threading.Tasks.TaskReplicator.Run[TState](ReplicatableUserAction`1 action, ParallelOptions options, Boolean stopOnFirstFailure)
   at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal](Partitioner`1 source, ParallelOptions parallelOptions, Action`1 simpleBody, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
--- End of stack trace from previous location ---
   at System.Threading.Tasks.Parallel.PartitionerForEachWorker[TSource,TLocal](Partitioner`1 source, ParallelOptions parallelOptions, Action`1 simpleBody, Action`2 bodyWithState, Action`3 bodyWithStateAndIndex, Func`4 bodyWithStateAndLocal, Func`5 bodyWithEverything, Func`1 localInit, Action`1 localFinally)
   at System.Threading.Tasks.Parallel.ForEach[TSource](Partitioner`1 source, Action`1 body)
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c__DisplayClass7_2.<GetUnreferencedObjects>b__2() in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1525
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
--- End of stack trace from previous location ---
   at System.Threading.ExecutionContext.RunFromThreadPoolDispatchLoop(Thread threadPoolThread, ExecutionContext executionContext, ContextCallback callback, Object state)
   at System.Threading.Tasks.Task.ExecuteWithThreadLocal(Task& currentTaskSlot, Thread threadPoolThread)
--- End of stack trace from previous location ---
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.GetUnreferencedObjects(UndertaleData data, Dictionary`2 typesDict) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1523
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.GetUnreferencedObjects(UndertaleData data, Dictionary`2 typesDict) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1594
   at UndertaleModTool.Windows.FindReferencesTypesDialog.SearchButton_Click(Object sender, RoutedEventArgs e) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\FindReferencesTypesDialog.xaml.cs:line 193
 ---> (Inner Exception #1) System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c.<.cctor>b__9_42(Object objSrc, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 455
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.GetReferencesOfObject(Object obj, UndertaleData data, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1418
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c__DisplayClass7_0.<GetUnreferencedObjects>b__3(Tuple`2 range) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1532
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
--- End of stack trace from previous location ---
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
   at System.Threading.Tasks.TaskReplicator.Replica.Execute()<---

 ---> (Inner Exception #2) System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c.<.cctor>b__9_42(Object objSrc, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 455
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.GetReferencesOfObject(Object obj, UndertaleData data, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1418
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c__DisplayClass7_0.<GetUnreferencedObjects>b__3(Tuple`2 range) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1532
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
--- End of stack trace from previous location ---
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
   at System.Threading.Tasks.TaskReplicator.Replica.Execute()<---

 ---> (Inner Exception #3) System.ArgumentNullException: Value cannot be null. (Parameter 'source')
   at System.Linq.ThrowHelper.ThrowArgumentNullException(ExceptionArgument argument)
   at System.Linq.Enumerable.Where[TSource](IEnumerable`1 source, Func`2 predicate)
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c.<.cctor>b__9_42(Object objSrc, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 455
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.GetReferencesOfObject(Object obj, UndertaleData data, HashSetTypesOverride types, Boolean checkOne) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1418
   at UndertaleModTool.Windows.UndertaleResourceReferenceMethodsMap.<>c__DisplayClass7_0.<GetUnreferencedObjects>b__3(Tuple`2 range) in D:\a\UndertaleModTool\UndertaleModTool\UndertaleModTool\Windows\FindReferencesTypesDialog\UndertaleResourceReferenceMethodsMap.cs:line 1532
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
--- End of stack trace from previous location ---
   at System.Threading.Tasks.Parallel.<>c__DisplayClass43_0`2.<PartitionerForEachWorker>b__1(IEnumerator& partitionState, Int64 timeout, Boolean& replicationDelegateYieldedBeforeCompletion)
   at System.Threading.Tasks.TaskReplicator.Replica.Execute()<---

Setup Details

1. UndertaleModTool 0.8.4.1
2. Windows 11 Home, 25H2; OS build 26200.7623; Experience Pack 1000.26100.275.0
3. Valdis Story: Abyssal City can be found on Steam here: https://store.steampowered.com/app/252030/Valdis_Story_Abyssal_City/
   game version 1.0.0.25; UMT reports internal version GMS 1.0.0.1224 bytecode 13

[ArchoDarko]

I'm also seeing random false positives in the "Find unreferenced assets" browser, except my results are some random strings and variables which probably are unused, except the false positives are all game objects, but it's not all of them.
If i go to "Search in code", I'm able to find almost all the unreferenced objects, except for the ones which are presumably default gamemaker objects (starting wth "Obj_").
Game i'm having this issue with is Please, Don't Touch Anything

[VladiStep]

Regarding the error - the reference searching code doesn't expect that the audio groups list is null (there are no audio groups in the file), which seems the case for GameMaker 1.0.0.1224.
It needs to be investigated more - what GameMaker versions don't have audio groups.

Updated: not the GameMaker version, but the bytecode version - audio groups are introduced for GameMaker versions with bytecode 14+:

[VladiStep]

Okay, as far as I can see, all the unreferenced assets (except "Code entries") are only referenced in the code, and the "Find all references" feature can't search in code for references, at least not for all common asset types such as game objects.
And the "Code entries" are gone from the latest 0.9.2.0 UTMT version (now it can see the rooms that use them).

That new version also states this in the references search results window:
"Note: the results may be not 100% correct and/or comprehensive.
Search in code as well via the "Find" menu if necessary.
(You may need to directly search for asset IDs, too.)"

Regarding the error - it will be fixed in #2467
@Crystal-Shard

[VladiStep]

ones which are presumably default gamemaker objects (starting wth "Obj_")

@ArchoDarko, as far as I know, there are no default GameMaker objects that start with "Obj_".
Could you provide a couple of such names?