`Resource Importers/ImportSounds.csx` InvalidOperationException (WPF)

[BioTomateDE]

Describe the bug

The UndertaleModTool GUI crashes with a InvalidOperationException when trying to use the ImportSounds script: "Added item does not appear at given index '304'.". This error occurs right after the script prints its success message.
Stacktrace (image): https://media.discordapp.net/attachments/586954521880690690/1449141796360687786/image.png

Original conversation:
Link: https://discord.com/channels/566861759210586112/586954521880690690/1449141796620992757
Guild: Underminers
Channel: #help
Date: 2025-12-12 20:52 UTC

Reproducing steps

1. Open Undertale in UndertaleModTool GUI
2. Use ImportSounds.csx
3. Select folder with WAV files
4. This script imports in bulk. Are you sure? > Yes
5. Replace sound properties? > No
6. Specify properties automatically? > Yes
7. Import OGG internal > No
8. If a sound exists it will be replaced > Ok
9. "Sounds successfully added"
10. Program successfully crashes

Setup Details

Tool Version: 0.8.2.0
OS: probably windows 10 or 11

idk, ask halfbreadchaos. im just the janitor.

[BioTomateDE]

the culprit might be line 179:

soundData = new UndertaleEmbeddedAudio() { Data = File.ReadAllBytes(file) };
Data.EmbeddedAudio.Add(soundData);
if (existingSound is not null)
{
    Data.EmbeddedAudio.Remove(existingSound.AudioFile); // HERE
}

idk how remove is handled, but if this shifts audio ids, its gonna be fucked.
my fix™ (without testing) would be to just replace the EmbeddedAudio sounddata instead adding then removing

[colinator27]

I can't reproduce this with the given steps. Removing an embedded audio entry should be totally fine, they're referred to by reference internally (and the IDs get resolved properly when saving).

[BioTomateDE]

that's weird. you should probably contact halfbreadchaos, they had this issue in the first place (I just did the bug report)