Rule Request: UnknownLabel

Not sure whether this is a PowerShell a bug or feature but fixing it in PowerShell would probably be a break change.

In any case, I think unknown labels should be notified and even deserve an error severity if the label doesn't exist or is outside the concerned loop.

Invoke-ScriptAnalyzer -ScriptDefinition {
    :foo foreach ($a in 1,2,3) {
        $a
        if ($a -ge $b) { break bar }
    }
}.ToString()

Expected
Something like:

RuleName           Severity     ScriptName Line  Message
--------           --------     ---------- ----  -------
PSUnknownLabel     Error                   4     The label 'bar' is not known in this context

See also: Pester breaks on functions with unknown label

先重現 Invoke-ScriptAnalyzer 範例，並檢查現有規則如何回報控制流程問題。確認未知標籤和位於相關迴圈之外的標籤在哪裡進行分析，然後驗證完成的規則是否針對該範例以 Error 嚴重性和預期訊息回報 PSUnknownLabel。