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

首先复现 Invoke-ScriptAnalyzer 示例，并检查现有规则如何报告控制流问题。确定未知标签和位于相关循环之外的标签在哪里进行分析，然后验证已完成的规则是否针对该示例以 Error 严重性和预期消息报告 PSUnknownLabel。