Crash when prompt is undefined in the runspace

[dkattan]

When "prompt" isn't defined in the runspace the fallback to DefaultPrompt doesn't work because we aren't catching the CommandNotFoundException

PowerShellEditorServices/src/PowerShellEditorServices/Services/PowerShell/Host/PsesInternalHost.cs

Lines 662 to 664 in b433b0f

	var command = new PSCommand().AddCommand("prompt");
	IReadOnlyList<string> results = InvokePSCommand<string>(command, PowerShellExecutionOptions.Default, cancellationToken);
	string prompt = results.Count > 0 ? results[0] : DefaultPrompt;

[JustinGrote]

Thanks! I don't want to know how you discovered this :P