Get object value by key, the value must be exist, otherwise the process will exit.

@param {KeyItem} key
@returns {Object}
function(key) {
        var obj = this.loadVar(key);
        if (!obj || typeof (obj) != 'object') {
            exitProcess('the value of ' +key+' is a necessary object ,but get '+ obj, this.alarm);
            return false;
        }
        return obj;
    }