[R] return inconsistency?

[Ralf Goertz]

I made a stupid error when programming a function. I used 

> return(OR^2+6*OR+1)/(OR*se^2)

Being parenthesis blind it took me half an hour to find the reason for
the nonsensical results I got. I should have written

> return((OR^2+6*OR+1)/(OR*se^2))

Having said that why is the first variant (which returns the value of
the numerator only) not a syntax error? I would have expected R to
report something like

> Error: unexpected '/' in "return(OR^2+6*OR+1)/"

If this is not an error what is its purpose?