added custom error page

Checklist

[x] My submission is formatted according to the guidelines in the contributing guide
[x] My submission has a useful description
[x] Code follows the established CODE_OF_CONDUCT guidelines.
[x] Code has been tested thoroughly.
[x] All commit messages are descriptive and follow the established commit message format.
[x] Pull request description clearly describes the changes included in the pull request.
[x] I have searched the repository for any relevant issues or pull requests
[x] Any category I am creating has the minimum requirement of 3 items