Be more defensive when reading statuspage incidents

[sciurus]

This tool is designed to

1. Never open more than one statuspage incident for a component
2. Never declare a statuspage incident as affecting more or less than one component

However, it should handle things properly if those conditions are violated. I think that means

1. Close the fist incident and log an error for each additional incident
2. Skip processing that incident, just as if it didn't have a component tag

[sciurus]

Note that in #19 I'm considering how to relax the constraint "Never declare a statuspage incident as affecting more or less than one component"