Error logs can help you troubleshoot bugs that can happen inside your chatbot. It can save you a lot of time trying to figure this out yourself otherwise.
To access the error log you can go to Tools from the left-hand menu, then select the first tab called Error logs.
From here you will have a complete overview of all errors that have happened in the chatbot.
From here you can see the date of the error, the kind of error, which user it affected, which sub flow it happened in along with the node that has the error, and more information.
If you press on the node of the error message it will take you directly to the point where the issue was registered at.
This will speed up troubleshooting immensely and save you hours you otherwise would waste in trying to find the bug.