PowerToys Run crashes with NullReferenceException when launching an unlaunchable MSIX/UWP app

### Microsoft PowerToys version

0.96.1.0

### Area(s) with issue

PowerToys Run / Program plugin

### Steps to reproduce

1. Have an MSIX/UWP app that Windows currently cannot launch. In my case it was the ChatGPT/Codex desktop app.
2. Open PowerToys Run with Alt+Space.
3. Search for the app and press Enter.
4. PowerToys Run crashes.

### Expected behavior

PowerToys Run should report that the app could not be launched and remain open.

### Actual behavior

PowerToys Run crashes with:

```text
System.NullReferenceException: Object reference not set to an instance of an object.
at Microsoft.Plugin.Program.Programs.UWPApplication.<>c__DisplayClass64_0.b__0()
at Microsoft.Plugin.Program.Programs.UWPApplication.Launch(IPublicAPI api, String queryArguments)
```

### Environment

```text
Windows 10.0.26200.0, x64
PowerToys 0.96.1.0
```

### Additional information

I reproduced this three times. Repairing the affected app in Windows Settings temporarily made it launchable again.

Start at Microsoft.Plugin.Program.Programs.UWPApplication.Launch, identified in the stack trace, and reproduce the failure with an unlaunchable MSIX/UWP app through PowerToys Run. Done means the app-launch failure is reported without a NullReferenceException and PowerToys Run remains open.

Written by the indexing model from the issue text.