Various extensions use OutputPage::addModules().
If a target field is not set on the module (defaults to desktop) and the module is run on mobile it is silently removed.
When this happens we should log it. It is important when we remove targets that it is effectively a no-op (no known violations).
At first this'll have to be log level "debug" to avoid flooding production with very common violations. Later level "warning" to find any less common ones in production.