Modern macOS App Icon Not Supported

[AeonSake]

Currently, the ElectronIcon property expects a file path which is then copied with the Copy instruction as a MSBuild task. However, the issue here is that the new/modern macOS app icon format .icon is actually just a folder (similar to how apps are also just folders with the .app extension). This format allows dynamic icons, grouping certain layers within the icon, applying different effects, and have platform-specific switches. The Copy instruction can only copy files, not directories, which causes the build to fail. Electron-builder itself has full support for the modern app icon format (see documentation) which is also the preferred format.

• NuGet Version: 0.4.1
• Electron Version: 41.0.3
• Electron Builder Version: 26.8.1
• Framework: net10.0
• Target: osx-arm64 (specified via publish profile)
• IDE: Visual Studio Code 1.111.0

electron_builder.json (relevant section only):

{
    "$schema": "https://raw.githubusercontent.com/electron-userland/electron-builder/refs/heads/master/packages/app-builder-lib/scheme.json",
    "mac": {
        "files": [ "**/*", "!mac*/*" ],
        "target": [ "dir" ],
        "icon": "icon.icon"
    }
}

Project configuration (relevant section only):

<PropertyGroup Label="ElectronNetCommon">
    <ElectronIcon>..\assets\icon.icon</ElectronIcon>
</PropertyGroup>

Current workaround:
Using the legacy format .icns and normal .png both work (but you lose all the possibilities of the modern format).