How do components fail?

How do components fail?

General rules with an answer per component type would be valuable.

We can work as a community to build up a single question that holds valuable information about how components fail.

Answer

Switches and pushbuttons: failure to make contact.

What you've listed looks like the severity part of an FMEA (Failure Mode and Effect Analysis), at least at component level. While it's not impossible, it's a hell of a job to account for every possible component failure if your design has, say, over a hundred components. One failing component may cause an avalanche of other components failing. Most failures aren't subtle.
You'll experience that adding components to cope with other components failing only adds complexity; you'll have to do an FMEA for these components as well!

An alternative approach, FMEA-wise, may be to start from occurrences. What's the MTTF (Mean Time To Failure)? Most components are quite robust; tens of thousands of POH (power-on hours) are feasable. (A notable weaker component is the Al elco, but even there are solutions). Anyway, an IC usually doesn't short just like that. So, while component failure may be caused by aging, most failures are caused by external factors, like overvoltage on the grid, or user error like misconnecting. Try to reduce these risks. Power spikes may be handled by overvoltage protection diodes. Misconnection can be avoided by using different connectors so that they can't be switched. Color code wires and use matching colors on connectors.

Bottom line: it may be more important to know why components fail than how they do.