sikebe-demo/dotnet-test-demo

AI Summary: Fix a bug in a Razor Pages application that causes a 500 Internal Server Error when accessing a non-existent GitHub user profile. The solution involves handling the 404 Not Found response from the GitHub API gracefully, displaying user-friendly error messages in both English and Japanese, and preventing application crashes. This includes modifying the `GithubClient` to check for a 404 response and return null, updating the `GithubProfileModel` to handle the null response and display appropriate error messages using resource files, and adding the necessary resource files for localization.