Use WeakReference to check if unload is successful

[Sardelka9515]

As pointed out in readme, the unload is performed asynchronously and won't always be successful, maybe we can use a WeakReference to guarantee the unload is successful before the loader is disposed, otherwise throw an exception. There's also an example implementation in the dotnet samples repository if you're interested.

[Tbeck-91]

this would be very useful

[github-actions[bot]]

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[github-actions[bot]]

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