### What?
See this issue - https://github.com/vercel/next.js/issues/61133
following this change https://github.com/vercel/next.js/pull/57815
`x-forwarded-port` header value is 'undefined' if the URL has no port
### Why?
x-forwarded-port 'undefined' makes other http-proxy throw 405 error for
the invalid header value
### How?
Give default 80 port if the URL has no port
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Co-authored-by: Ethan Arrowood <ethan@arrowood.dev>
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