When using server middlewares content type disappears inside managementUI

[0x77dev]

When using a custom middleware (in my scenario for auth purposes) in the ~/server folder, managementUI breaks. It seems like the content type is not set correctly, causing pages to show plain text instead of HTML and etc.

To reproduce just place any middleware in server, like for example:

import { getServerSession } from "#auth"

export default defineEventHandler(async (event) => {
  const url = getRequestURL(event)
  if (!url.pathname.startsWith('/_concierge')) return

  const auth = await getServerSession(event)

  if (!auth) {
    return sendRedirect(event, '/auth/signin?callbackUrl=' + encodeURIComponent(url.pathname + url.search))
  }
})

Bad Workaround in my scenario looks like this (seriously, don't do this):

import { getServerSession } from "#auth"

export default defineEventHandler(async (event) => {
  const url = getRequestURL(event)
  if (!url.pathname.startsWith('/_concierge')) return

  const auth = await getServerSession(event)

  if (!auth) {
    return sendRedirect(event, '/auth/signin?callbackUrl=' + encodeURIComponent(url.pathname + url.search))
  }

  // set appropriate headers for files, since it is broken by middleware
  // TODO: remove this hack
  const contentMap = {
    'css': 'text/css',
    'js': 'text/javascript',
    'html': 'text/html',
    'json': 'application/json',
    'svg': 'image/svg+xml',
  }

  if (url.pathname.startsWith('/_concierge/api')) {
    setResponseHeaders(event, {
      'Content-Type': 'application/json',
    })
  } else {
    const type = url.pathname.split('.').pop() || 'html'
    const customContentType = contentMap[type as keyof typeof contentMap] || 'text/html'
    setResponseHeaders(event, {
      'Content-Type': customContentType,
    })
  }
})