fix: request url no forwarded host

.changeset/modern-baboons-build.md

@@ -0,0 +1,5 @@
+---
+"frog": patch
+---
+
+Fixed a regression in local environments with templates other than `next` used where port was deleted when `X-Forwarded-Host` was not present that resulted in a malformed `postUrl` and `image` url values in the rendered frame meta tags. 

src/utils/getRequestUrl.ts

@@ -5,6 +5,7 @@ export function getRequestUrl(req: Context['req']) {
   const forwardedHost = req.header('x-forwarded-host')
   url.host = forwardedHost ?? url.host
   url.protocol = req.header('x-forwarded-proto') ?? url.protocol
-  if (!forwardedHost?.startsWith('localhost')) url.port = ''
+  if (forwardedHost !== undefined && !forwardedHost.startsWith('localhost'))
+    url.port = ''
   return url
 }