Improve getDapp method error handling

[bobo-k2]

Pull Request Summary

Fixed error 404 handling for getDapp method

Check list

• [ ] contains breaking changes
• [ ] adds new feature
• [x] modifies existing feature (bug fix or improvements)
• [ ] relies on other tasks
• [ ] documentation changes
• [ ] tested on mobile devices

[github-actions[bot]]

Visit the preview URL for this PR (updated for commit 17ce355):

https://astar-apps--pr1307-fix-get-dapp-error-h-exsuvf5p.web.app

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