use react route to handle bad url extension code example
Example: can't bookmark react router
// Add the following to .htaccess file in the public folder
// NOTE: This is for Apache servers!
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.html$ - [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !-l
RewriteRule . /index.html [L]
</IfModule>