Subapp error handler is not respected

[v1rtl]

Reproduction:

import { App } from 'https://denopkg.com/deno-libs/tinyhttp@master/mod.ts'
import { makeFetch } from 'https://deno.land/x/superfetch@1.0.4/mod.ts'

const app = new App({
  onError: (err, req) =>
  new Response(`Ouch, ${err} hurt me on ${req?.url} page.`, {
    status: 500,
  })
})

const subApp = new App({
  onError: (err, req) =>
  new Response(`Handling ${err} from child on ${req?.url} page.`, {
    status: 500,
  })
})

subApp.get('/route', async (req, res, next) => await next('you'))

app.use('/subapp', subApp)

const server = app.handler
const fetch = makeFetch(server)

const res = await fetch('/subapp/route')
res.expectStatus(500).expectBody('Handling you from child on /subapp/route page.')

[aarontravass]

shouldn't the last test throw a 404?

  it('lets other wares handle the URL if subapp doesnt have that path', async () => {
    const app = new App()

    const subApp = new App()

    subApp.get('/route', (_, res) => void res.end(subApp.mountpath))

    app.use('/test', subApp)

    app.use('/test3', (req, res) => void res.end(req.url))

   // const fetch1 = makeFetch(app.handler)

    //const res1 = await fetch1('/test/route')
    //res1.expect('/test')
    const fetch2 = makeFetch(app.handler)
    const res2 = await fetch2('/test3/abc')
    res2.expect('http://localhost:8080/test3/abc')
  })