The possibility of a squib seriously challenges the standard tap-rack-bang drill. Only do that if you are in a real shootout. Otherwise, be sure to inspect the round that only clicked! One hopes to see a complete round in there ...
A squib and a misfire (tap and rack) sound completely different. Click vs pop. But yes, a tap and rack on a squib would likely be not pretty.
Fortunately, in both cases, the squib had not travelled far enough into the barrel to allow the following round to chamber. We surmise it was a case of no powder thrown and only the primer had the enrgy for the light squib.