PSAvoidAssignmentToAutomaticVariable generates false positives during script analysis

首先透過 PSScriptAnalyzer 執行提供的 Write-Log 函式，並檢查回報 $Error 參數的 PSAvoidAssignmentToAutomaticVariable 規則。根據所述的 PowerShell 範圍行為確認診斷；完成的標準是此情況不再被回報，且如果該診斷在其他地方仍然適用，則修正診斷文字。

Steps to reproduce

Run this function through PSSA.

function Write-Log {
    [CmdletBinding()]
    param
    (
        [Parameter(Position = 0, Mandatory)]
        [ValidateNotNullOrEmpty()]
        [string]
        $Message,

        [switch]
        $Error
    )
    $callerEAP = $ErrorActionPreference
    try {
        $messageColor = if ($PSCmdlet.MyInvocation.BoundParameters.ContainsKey('Error') -and $Error) {
            [ConsoleColor]::Red
        } else {
            [ConsoleColor]::Cyan
        }

        Write-Host -Foreground $messageColor -Object $Message

        # Reset colors to return to default after an error message on a compilation error
        [System.Console]::ResetColor()
    } catch {
        Write-Error -ErrorRecord $_ -ErrorAction $callerEAP
    }
}

Expected behavior

It passes.

Actual behavior

PSSA reports the following:

The Variable 'Error' cannot be assigned since it is a readonly automatic variable that is built into PowerShell, please use a different name.

There are a number of problems with this:

1. The comma should be a period for it to read properly.
2. The error text is incorrect. $Error can be assigned in child scopes without issue. $Error is read-only only in the global scope, and errors are automatically written into that globally-scoped collection that is read-only from PowerShell. In functions, or child scopes, you can use a $Error variable to your hearts content.
3. Most importantly: the issue that is being called out by PSSA here should not be called out at all.

Environment data

> $PSVersionTable
Name                           Value
----                           -----
PSVersion                      7.0.1
PSEdition                      Core
GitCommitId                    7.0.1
OS                             Microsoft Windows 10.0.18363
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() }
1.19.0