You may say that users don't need to see to see strange error messages they don't understand. Quite right, what we need instead is to have a way for browsers to transmit uncaught exceptions in JS to the server.
It just doesn't seem like something that would happen accidentally, there's no reason to put + on something unless you are explicitly trying to coerce it into a number. It's not like unary minus where -x; could have some other semantic meaning for something that is already a number and you make a mistake and give it an array (which javascript has, and I think is a much more likely source of error than the unary plus).
If I want an array to be a number, I'll call .Count on the array or whatever the applicable property I want is.
The unary '+' operator is completely pointless if something is already a number, it is a no-op. Literally the only time anyone would ever type +x is if x is not a number, if someone chose to write +x and x turned out to unexpectedly be an array, pretty much the only thing that you know they were thinking of when they wrote the + was that they thought x isn't a number; maybe a string if they were using +x instead of parseFloat(x), but definitely not a number.
It just isn't a reasonable example of a situation where an array is being used where a number should be, +x where you know that x is a number would make no sense. If you talk about -x then that is completely different, people who write -x almost certainly expect it to be a number, and -[] === 0. Unary plus is just not the right example for awful type coercion here.
http://en.wikipedia.org/wiki/Division_by_zero#In_computer_ar...