NullReferenceException analyzing xWebAdministration DSC resource

[edyoung]

Steps to reproduce

save-module -Name xWebAdministration -Version 1.20.0.0 -Path .
Invoke-ScriptAnalyzer .

Expected behavior

some warnings if warranted

Actual behavior

Numerous errors, including the NullReferenceException below:
writeErrorStream      : True
PSMessageDetails      :
Exception             : System.NullReferenceException: Object reference not set to an instance of an object.
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseIdenticalMandatoryPa
                        rametersDSC.GetKeys(String fileName)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseIdenticalMandatoryPa
                        rametersDSC.<AnalyzeDSCResource>d__7.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.AnalyzeSyntaxTree(Scr
                        iptBlockAst scriptAst, Token[] scriptTokens, String filePath)
TargetObject          : C:\temp\testpackages\xWebAdministration\1.20.0.0\DSCResources\MSFT_xWebsite\MSFT_xWebs
                        ite.psm1
CategoryInfo          : InvalidOperation: (C:\temp\testpac...T_xWebsite.psm1:String) [Invoke-ScriptAnalyzer],
                        NullReferenceException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCo
                        mmand
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {0, 1}
writeErrorStream      : True
PSMessageDetails      :
Exception             : System.NullReferenceException: Object reference not set to an instance of an object.
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseIdenticalMandatoryPa
                        rametersDSC.GetKeys(String fileName)
                           at Microsoft.Windows.PowerShell.ScriptAnalyzer.BuiltinRules.UseIdenticalMandatoryPa
                        rametersDSC.<AnalyzeDSCResource>d__7.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.AnalyzeSyntaxTree(Scr
                        iptBlockAst scriptAst, Token[] scriptTokens, String filePath)
TargetObject          : C:\temp\testpackages\xWebAdministration\1.20.0.0\DSCResources\MSFT_xWebApplication\MSF
                        T_xWebApplication.psm1
CategoryInfo          : InvalidOperation: (C:\temp\testpac...pplication.psm1:String) [Invoke-ScriptAnalyzer],
                        NullReferenceException
FullyQualifiedErrorId : RULE_ERROR,Microsoft.Windows.PowerShell.ScriptAnalyzer.Commands.InvokeScriptAnalyzerCo
                        mmand
ErrorDetails          :
InvocationInfo        : System.Management.Automation.InvocationInfo
ScriptStackTrace      : at <ScriptBlock>, <No file>: line 1
PipelineIterationInfo : {0, 1}

Environment data

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      5.1.16299.251
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.16299.251
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1

> (Get-Module -ListAvailable PSScriptAnalyzer).Version | ForEach-Object { $_.ToString() }
1.16.1

[bergmeister]

I can confirm this still happens on the latest version of development. The more minimal repro is:

save-module -Name xWebAdministration -RequiredVersion 1.20.0.0 -Path .
$results = Invoke-ScriptAnalyzer -Path .\xWebAdministration\1.20.0.0\DSCResources\MSFT_xWebApplication

Here is the snapshot inside the debugger: