async/await: async void causes unhandled exceptions that crash the process

Methods declared async void fire-and-forget. Any exception thrown inside them propagates to the synchronization context and typically crashes the application or is silently swallowed — it cannot be caught at the call site.

Always return Task or Task<T> from async methods. Use async void only for event handlers where the signature is forced:

// BAD
public async void LoadData() // exception escapes, can't be awaited
{
    await FetchAsync();
}

// GOOD
public async Task LoadDataAsync()
{
    await FetchAsync();
}

// Event handler — only acceptable async void use
private async void Button_Click(object sender, EventArgs e)
{
    try { await LoadDataAsync(); }
    catch (Exception ex) { ShowError(ex); } // must catch explicitly
}

async void methods cannot be awaited by callers, so exceptions propagate through whatever SynchronizationContext was active when the method started. In ASP.NET Core (no SynchronizationContext) this triggers TaskScheduler.UnobservedTaskException and may crash the process.