UseCorrectCasing gets NullReferenceException from CommandInfo.get_Parameters

Steps to reproduce

This reproduces about 25% of the time on my laptop. I think we may be exposing a gap in the fix for #1516, perhaps because we have about 250 .ps1 files in the repo.

• Clone https://github.com/microsoft/CSS-Exchange
• Change into that folder and run:

Get-ChildItem *.ps1 -Recurse | % { Invoke-ScriptAnalyzer -Path $_ -Settings .\PSScriptAnalyzerSettings.psd1 }

• If it doesn't reproduce on the first try, launch a new PowerShell window, cd into the folder, and try again.

Expected behavior

No error.

Actual behavior

Invoke-ScriptAnalyzer: Object reference not set to an instance of an object.

If an unexpected error was thrown then please report the full error details using e.g. $error[0] | Select-Object *

PSMessageDetails      :
Exception             : System.NullReferenceException: Object reference not set to an instance of an object.
                           at System.Management.Automation.CommandInfo.get_Parameters()
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseCorrectCasing.AnalyzeScript(Ast ast, String fileName)+MoveNext()
                           at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
                           at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer.<>c__DisplayClass82_1.<AnalyzeSyntaxTree>b__2()
TargetObject          : D:\code\CSS-Exchange\Diagnostics\ExchangeLogCollector\RemoteScriptBlock\IO\Copy-BulkItems.ps1
CategoryInfo          : InvalidOperation: (D:\code\CSS-Exchang…\Copy-BulkItems.ps1:String) [Invoke-ScriptAnalyzer], NullReferenceException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
                        at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {0, 1}

❯ Get-Error $Error[0]

Exception             :
    Type       : System.NullReferenceException
    TargetSite :
        Name          : get_Parameters
        DeclaringType : System.Management.Automation.CommandInfo
        MemberType    : Method
        Module        : System.Management.Automation.dll
    StackTrace :
   at System.Management.Automation.CommandInfo.get_Parameters()
   at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseCorrectCasing.AnalyzeScript(Ast ast, String fileName)+MoveNext()
   at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
   at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
   at Microsoft.Windows.PowerShell.ScriptAnalyzer.ScriptAnalyzer.<>c__DisplayClass82_1.<AnalyzeSyntaxTree>b__2()
    Message    : Object reference not set to an instance of an object.
    Source     : System.Management.Automation
    HResult    : -2147467261
TargetObject          : D:\code\CSS-Exchange\Diagnostics\ExchangeLogCollector\RemoteScriptBlock\IO\Copy-BulkItems.ps1
CategoryInfo          : InvalidOperation: (D:\code\CSS-Exchang…\Copy-BulkItems.ps1:String) [Invoke-ScriptAnalyzer], NullReferenceException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCommand
InvocationInfo        :
    MyCommand        : Invoke-ScriptAnalyzer
    ScriptLineNumber : 1
    OffsetInLine     : 36
    HistoryId        : 2
    Line             : Get-ChildItem *.ps1 -Recurse | % { Invoke-ScriptAnalyzer -Path $_ -Settings .\PSScriptAnalyzerSettings.psd1 }
    PositionMessage  : At line:1 char:36
                       + … curse | % { Invoke-ScriptAnalyzer -Path $_ -Settings .\PSScriptAnalyz …
                       +               ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
    InvocationName   : Invoke-ScriptAnalyzer
    CommandOrigin    : Internal
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
                        at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo :

Environment data

> $PSVersionTable

Name                           Value
----                           -----
PSVersion                      7.1.3
PSEdition                      Core
GitCommitId                    7.1.3
OS                             Microsoft Windows 10.0.19043
Platform                       Win32NT
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0…}
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1
WSManStackVersion              3.0

> (Get-Module -ListAvailable PSScriptAnalyzer).Version | ForEach-Object { $_.ToString() }

1.19.1

首先针对 CSS-Exchange 仓库复现 PowerShell 命令，然后检查 BuiltinRules/UseCorrectCasing 及其堆栈跟踪中指定的 AnalyzeScript 入口点。跟踪如何到达 CommandInfo.get_Parameters，并验证分析器在整个仓库的 .ps1 文件上都能完成运行且不会出现 NullReferenceException。