Empty statistics and JS console errors

Problem/Motivation

I tested the module on simplytest.me with core 10.3.6
I created an Image type Advertisment and placed to content region as SimpleAds block. After clicking on the advertisment the "All Time", "Last 30 days" and "Last week" charts on the /admin/content/simpleads/1 are empty and there are some JS errors in console:
Invalid scale configuration for scale: xAxes
Invalid scale configuration for scale: yAxes

Steps to reproduce

1. start a test on simplytest.me with core 10.3.6 and Simpleads 2.0.11
2. create an Image type Advertisment on /admin/content/simpleads/add page
3. place the SimpleAds anywhere
4. click on the image of the advertisment
5. go to /admin/content/simpleads/1