fix: empty links directed to '/.html' (fix #105)

[lirc572]

Summary

fixes #105

NavLink component now routes to '' if link prop is empty or only contains whitespaces (no redirection).

Now, clicking on copyright section in the footer does not cause redirection to '/.html'.

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• [x] Bugfix
• [ ] Feature
• [ ] Code style update
• [ ] Refactor
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Other information:

[billyyyyy3320]

Opened #111

[lirc572]

Thanks! Plain-text copyright info looks nice!

Although this is not important, I still think it is erroneous for NavLink to append '.html' to an empty path. Maybe an empty link can serve as a placeholder?