Steps to reproduce:

Create a new 3D (URP) project via Unity Hub
Do NOT install the "Project Auditor Rules" package (a new project does not have it - this is the default state; Project Auditor itself is built into the Editor)
Create the folder Assets/Editor and add the script AuditRepro.cs from the attached repro project (it calls "new ProjectAuditor().Audit()" and logs the issue count)
In the menu bar, select Repro > Run Scripted Audit
Observe the Console window

Actual results: Audit() completes instantly and returns a Report with 0 issues. No exception is thrown and no warning is logged. Nothing indicates that no analysis actually ran (zero analysis modules are initialized when the Rules package is missing).
Console: "Audit() returned normally: 0 issues, no exception, no warning"

Expected results: Audit() treats the missing Rules package the same way the rest of Project Auditor already does: the Project Auditor window (Window > Analysis > Project Auditor) gates all analysis behind an "Install Rules" button, and ProjectAuditor.KnownUnityVersions throws InvalidOperationException ("Install the Project Auditor Rules package before using Project Auditor"). Audit() should throw the same exception, or at minimum log a warning - not return a successful empty report.

Reproducible with versions: 6000.5.8f1, 6000.6.0f1, 6000.7.0a6

Not reproducible with versions: 6000.0.82f1, 6000.3.18f1

Tested on (OS): Windows 11