First of all thanks for making the effort and improvement. I agree that throwing a terminating error here is the right decision. One minor comment but hold off from addressing it at the moment, I will add more reviewers so that they can decide as well. But otherwise, it looks good to me. In the future we might enhance it to emit DiagnosticRecords of type ParserError in lower levels so that people get highlighting in VS Code but your change to improve the command line experience is good as a first improvement.
The red Ubuntu build can be ignored for the moment, this is a problem with the recent image update in AppVeyor that is also affecting the maindevelopment branch.
With the recently merged PR#1250, which improves the exceptions that are reported, this gives us now nice messages like this@JamesWTruher :-)

Invoke-ScriptAnalyzer -ScriptDefinition gci  -Settings @{foo='bar'}Invoke-ScriptAnalyzer : foo is not a valid key in the settings hashtable. Valid keys are ExcludeRules, IncludeRules and Severity.At line:1 char:2+  Invoke-ScriptAnalyzer -ScriptDefinition gci  -Settings @{foo='bar'}+  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~+ CategoryInfo          : InvalidData: (System.Collections.Hashtable:Hashtable) [Invoke-ScriptAnalyzer], InvalidDataException+ FullyQualifiedErrorId : InvalidSettingsData,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand

I think@JamesWTruher was working on something in this space as well.

Ideally this should actually throw anAggregateException and tell youall of the configuration problems (that's the general pattern for a parser, so you can fix as much as possible).

But I think this is a step in the right direction.

Thanks, looks good to me, just one minor cleanup nit