Activate on satisfying a condition question

Activate on satisfying a condition question

Hi, 

I'd like to use the "Activate on satisfying a condition" option of the "Experiment Activation Mode"..

I created this condition: 

document.querySelector("div.location-top-data a.btn.blue.radius.xsmall").innerHTML == "Contact Us";

The idea is that the experiment only runs when this condition is satisfied. 

Question: the website contains pages where this same element div.location-top-data a.btn.blue.radius.xsmall is not there. Testing the script on these pages, at Chrome console, I receive this message: 

Uncaught TypeError: Cannot read property 'innerHTML' of null at <anonymous>:1:73

Is it OK that this script return this or must return "false"? Wondering if that could potentially cause any issues at pages where the element is not there. 

Thanks!