Alax/Javascript bugs are everywhere

Recently, I am working with teams doing tons of "usability" focused coding, which requires massive use of Javascript and Ajax. Besides the security problems, which are enormous (see this tutorial from Google about it: http://jarlsberg.appspot.com/), you have to deal with the unpredictable common-sense of the end-user, which is IMO, never as easy as it could be.

So, whenever I think about the bugs and problems we face all day because of it, I look back to giants and see that, even with all the power in their hands, still simple problems such as below keep showing up...

 
My gmail (yes, Gmail) account displaying zero messages (I just deleted the spam) but with some calculation errors (probably just a variable that was not updated in time)... But this bug caused my click to the "Older >" to get interestingly going forward on zero messages...

"To err is human, to forgive divine." -- Alexander Pope