localeSubpaths generate TypeError in force-trailing-slash.js

I just try to run the source example with localeSubpaths set to true

Here is my i18n.js (only change made)

const NextI18Next = require('next-i18next')

module.exports = new NextI18Next({
	otherLanguages: ['de'],
	localeSubpaths: true
})

And then, each page load result in lots of warning in the shell

TypeError: Cannot read property 'options' of undefined
    at _default (...\node_modules\next-i18next\dist\utils\force-trailing-slash.js:15:12)

— (the full trace is too long and not really usefull) —

Page generation still work and translation are in place, but kinda worry about all those warnings about a missing i18n object

https://github.com/isaachinman/next-i18next/blob/master/src/utils/force-trailing-slash.js (line 5)

req.i18n.options.allLanguages.forEach((lng) => {

[isaachinman]

That’s not an additional problem, that’s the same problem. Fix coming shortly.

[isaachinman]

Basic e2e testing added with 08b0449.