This is not an issue but a problem with your code. Issues are problem caused by defects in the kata itself. You'd rather ask a question in this case. However with no more elements, it's impossible to help you. I guess you're using Python. Actually you don't pass all tests, they give up once they meet an error. KeyError means you try to access a key that does not exist in a dictionary or a similar object, and Python crashes in those cases. Hopefully this may help you: Troubleshooting Your Solution.

All my tests are passed but one got terminated because of key error.What to do?