Fix and reenable windows scope-hoisting tests

[mischnic]

↪️ Pull Request

The scopehoisting test on Windows were disabled because the afterEach test hook deleting the dist folder failed with a permissions error.
This was because JSConcatPackager.end() didn't call super.end() to close the file handle (no issues on macOS / Linux).

I also wrapped the call to concat and everything thereafter in a try-catch, because let {code: output} = concat(this, ast); can throw because of e.g. a missing import, meaning super.end() would never be called.

💻 Examples

🚨 Test instructions

✔️ PR Todo

• Added/updated unit tests for this change
• Filled out test instructions (In case there aren't any unit tests)
• Included links to related issues/PRs