In settings.py, added 'chocoberrie.pythonanywhere.com' to the ALLOWED_HOSTS list, and I made sure to include it in quotation marks and keep the brackets. I even added it to requests.py, at line 113 (indicated in the error message).
I also committed the changes to Git, and I double-checked the repository to make sure that the URL was added to ALLOWED_HOSTS. (It was.) And of course, I reuploaded the changes on PythonAnywhere too.
After all that, I'm still getting the error! It's really frustrating, and I don't know what else to do. Any help would be much appreciated!