Hi, Anna-Mariya. Sorry you’re experiencing this.
This sounds like a past issue that required The Events Calendar be installed, which has since been fixed.
I looked at Line 49 of that file and it doesn’t match the version you’re using so I’m hopeful updating to the latest versions will resolve this for you.
Could you please make sure all your Modern Tribe plugins (and WordPress core) are at their latest versions?
Once you verify you’re on the latest versions, please test to see if the issue is still happening for you.
Let us know what you find out.
Thanks.