sending to a channel before opening it doesn't create an error

[enaaab460]

I have mistakenly, multiple times, sent items to a channel after initialising 
it but before opening it. The compiler never complained. After the program 
compiles and runs, it gets a SIGSEGV which I then discover my mistake.

It would be very helpful it the compiler produced an error (like the type 
mismatch error when you use the wrong function signature)

simplified example
    
    
    var
        cc:Channel[int]
    
    cc.send 1
    cc.open
    
    
    Run

This compiles without error