can.compute error with can.Observe

https://github.com/bitovi/canjs/blob/master/observe/compute/compute.js#L338

    if( can.Observe.__reading && canReadForChangeEvent) {
        can.Observe.__reading(computed,'change');
    }

This conditional assumes can.Observe exists. Just need an extra if(can.Observe && can.Observe.__reading...

Noting this until I get back to it(unless someone beats me to this!)