Anyone who can help a newbie with a suitescript2.0 training question? Getting a reference error and not sure what is wrong

ask the actual question

Just unsure what is causing the Reference Error in the following script, again new to SuiteScript & JavaScript so any advice would be appreciated

function fieldChanged(context) {
        var customer = context.newRecord
        var applyCoupon = customer.getValue('custentity_sdr_apply_coupon');
        var couponCode = customer.getValue('custentity_sdr_coupon_code');
        //if apply coupon is checked enable coupon code, if unchecked disable coupon code and erase its content
        if (!applyCoupon) {couponCode.isDisabled = true;
        } else {couponCode.isDisabled = false;
        }

    }

you should share the actual error

gotcha that makes sense, I appreciate the help

you still probably want to share that error, my comment was more in general