Add source mapping for errors in `routes.match`

[EECOLOR]

This can be done in the template (hacked version):

Object.assign(
  render,
  withSourceMap(template),
)

function withSourceMap(template) {
  console.log(template)
  return mapValues(template, x =>
    typeof x === 'function' ? (...args) => withSourceMappedErrorAsync(createMap, () => x(...args)) :
    x && typeof x === 'object' ? withSourceMap(x) : x
  )
}
function mapValues(x, f) {
  return Object.entries(x)
    .map(([k, v]) => [k, f(v, k, x)])
    .reduce((result, [k, v]) => ({ ...result, [k]: v }), {})
}
...
function withSourceMappedErrorAsync(createMap, fn, options) {
  return withRawErrorStackAsync(async () => {
    try {
      return await fn()
    } catch (e) {
      const messageWithStack = e + '\n' + toMappedStack(createMap, e.stack, options)
      const error = new Error(messageWithStack)
      error.stack = messageWithStack
      throw error
    }
  })
}
async function withRawErrorStackAsync(fn) {
  const $prepareStackTrace = Error.prepareStackTrace
  Error.prepareStackTrace = (error, stack) => stack
  try { return await fn() } finally { Error.prepareStackTrace = $prepareStackTrace }
}

Another option would be to call the function with source mapped error from serve.