Errors should never pass describes the case of AppArmour which fails to follow the Rule of Repair. In this particular case, AppArmor could not make sense of the user (config) input – and thus cannot repair the data-, so it should fail as noisily and as soon as possible to prevent debugging nightmares.
Grails is another example of a framework that fails to follow this rule (at least until v1.1, I cannot speak for v1.2). I have way too often seen situations where the input was clearly incorrect (e.g. spring builder configuration) and grails was not reporting any error, and was injecting null values instead.
Note: this rule is part of the Art of unix programming, and thus part of the design principles I believe in (previous post).
