When I originally wrote "When to scream 'Error!'", I was mainly thinking of bad patterns of thought or bad problem-solving strategies as being the source of the error. Since then, I've come to realize that my own most common source of stupidity is because I've neglected some comfort. I may be hungry without consciously paying attention to it, dehydrated because I've been living on coffee for too long, or simply have a headache and need to take an Ibuprofen -- as a result, I don't think well, get irritated at the fact that I'm not thinking well, and generally begin a death spiral if I don't realize why.

In hindsight, it feels obvious that I should take care of the physiological needs that I can because they're likely preventing me from thinking straight. However, I've failed to do this on numerous occasions and so thought it worth mentioning.

In summary: Whenever you're screaming "Error", I suggest you stop and figure out whether you're hungry, thirsty, tired, or hurting before trying to find a problem in your thinking itself, especially if you're not usually good at noticing such things.